Properly initializing reserved pointer in tests.
diff --git a/test/core/end2end/tests/bad_hostname.c b/test/core/end2end/tests/bad_hostname.c
index a35923c..2442200 100644
--- a/test/core/end2end/tests/bad_hostname.c
+++ b/test/core/end2end/tests/bad_hostname.c
@@ -128,13 +128,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -142,6 +145,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/cancel_after_accept.c b/test/core/end2end/tests/cancel_after_accept.c
index db391b8..1583a06 100644
--- a/test/core/end2end/tests/cancel_after_accept.c
+++ b/test/core/end2end/tests/cancel_after_accept.c
@@ -144,22 +144,27 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -174,18 +179,22 @@
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(3), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
index 579fe7f..30bb92e 100644
--- a/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
+++ b/test/core/end2end/tests/cancel_after_accept_and_writes_closed.c
@@ -144,25 +144,31 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -177,18 +183,22 @@
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(3), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/cancel_after_invoke.c b/test/core/end2end/tests/cancel_after_invoke.c
index afb51a0..b25395d 100644
--- a/test/core/end2end/tests/cancel_after_invoke.c
+++ b/test/core/end2end/tests/cancel_after_invoke.c
@@ -139,25 +139,31 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, test_ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/cancel_before_invoke.c b/test/core/end2end/tests/cancel_before_invoke.c
index 55a6555..fd7bca9 100644
--- a/test/core/end2end/tests/cancel_before_invoke.c
+++ b/test/core/end2end/tests/cancel_before_invoke.c
@@ -139,25 +139,31 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, test_ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/census_simple_request.c b/test/core/end2end/tests/census_simple_request.c
index 8ae1314..44241d1 100644
--- a/test/core/end2end/tests/census_simple_request.c
+++ b/test/core/end2end/tests/census_simple_request.c
@@ -126,13 +126,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -140,6 +143,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -155,16 +159,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/disappearing_server.c b/test/core/end2end/tests/disappearing_server.c
index d1cee7b..52ef23e 100644
--- a/test/core/end2end/tests/disappearing_server.c
+++ b/test/core/end2end/tests/disappearing_server.c
@@ -111,13 +111,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -125,6 +128,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -144,16 +148,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
index ff8dd8c..4317c57 100644
--- a/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
+++ b/test/core/end2end/tests/early_server_shutdown_finishes_inflight_calls.c
@@ -120,13 +120,16 @@
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -134,6 +137,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -149,6 +153,7 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/graceful_server_shutdown.c b/test/core/end2end/tests/graceful_server_shutdown.c
index cb1b730..1ce85f2 100644
--- a/test/core/end2end/tests/graceful_server_shutdown.c
+++ b/test/core/end2end/tests/graceful_server_shutdown.c
@@ -127,13 +127,16 @@
   op->data.send_initial_metadata.count = 0;
   op->data.send_initial_metadata.metadata = NULL;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -141,6 +144,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -160,16 +164,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/invoke_large_request.c b/test/core/end2end/tests/invoke_large_request.c
index 2e517fa..0b2f3a0 100644
--- a/test/core/end2end/tests/invoke_large_request.c
+++ b/test/core/end2end/tests/invoke_large_request.c
@@ -143,21 +143,26 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -165,6 +170,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -180,10 +186,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -195,16 +203,19 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/max_concurrent_streams.c b/test/core/end2end/tests/max_concurrent_streams.c
index 88ab7b1..df24c6e 100644
--- a/test/core/end2end/tests/max_concurrent_streams.c
+++ b/test/core/end2end/tests/max_concurrent_streams.c
@@ -128,13 +128,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -142,6 +145,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -157,16 +161,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -265,9 +272,11 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c1, ops, op - ops, tag(301), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -279,10 +288,12 @@
   op->data.recv_status_on_client.status_details = &details1;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c1, ops, op - ops, tag(302), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -291,9 +302,11 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c2, ops, op - ops, tag(401), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -305,10 +318,12 @@
   op->data.recv_status_on_client.status_details = &details2;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity2;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv1;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c2, ops, op - ops, tag(402), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -341,16 +356,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s1, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -372,16 +390,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s2, ops, op - ops, tag(202), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/max_message_length.c b/test/core/end2end/tests/max_message_length.c
index c022eb9..c7a5a60 100644
--- a/test/core/end2end/tests/max_message_length.c
+++ b/test/core/end2end/tests/max_message_length.c
@@ -144,17 +144,21 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -162,6 +166,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -177,6 +182,7 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/ping_pong_streaming.c b/test/core/end2end/tests/ping_pong_streaming.c
index a67fac1..93599e1 100644
--- a/test/core/end2end/tests/ping_pong_streaming.c
+++ b/test/core/end2end/tests/ping_pong_streaming.c
@@ -139,10 +139,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -150,6 +152,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -165,10 +168,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(101), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -181,10 +186,12 @@
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = request_payload;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &response_payload_recv;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
     error = grpc_call_start_batch(c, ops, op - ops, tag(2), NULL);
     GPR_ASSERT(GRPC_CALL_OK == error);
@@ -193,6 +200,7 @@
     op->op = GRPC_OP_RECV_MESSAGE;
     op->data.recv_message = &request_payload_recv;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
     error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
     GPR_ASSERT(GRPC_CALL_OK == error);
@@ -203,6 +211,7 @@
     op->op = GRPC_OP_SEND_MESSAGE;
     op->data.send_message = response_payload;
     op->flags = 0;
+    op->reserved = NULL;
     op++;
     error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
     GPR_ASSERT(GRPC_CALL_OK == error);
@@ -222,6 +231,7 @@
   op = ops;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(3), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -232,6 +242,7 @@
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(104), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/registered_call.c b/test/core/end2end/tests/registered_call.c
index 0ffae8c..a83ccdd 100644
--- a/test/core/end2end/tests/registered_call.c
+++ b/test/core/end2end/tests/registered_call.c
@@ -129,13 +129,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -143,6 +146,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -158,16 +162,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
index 48fb096..7bc922f 100644
--- a/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_binary_metadata_and_payload.c
@@ -163,21 +163,26 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -185,6 +190,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -201,10 +207,12 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -216,16 +224,19 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_response_with_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
index c28173c..d3362b4 100644
--- a/test/core/end2end/tests/request_response_with_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_metadata_and_payload.c
@@ -145,21 +145,26 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -167,6 +172,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -183,10 +189,12 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -198,16 +206,19 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_response_with_payload.c b/test/core/end2end/tests/request_response_with_payload.c
index d21d5fa..6badbde 100644
--- a/test/core/end2end/tests/request_response_with_payload.c
+++ b/test/core/end2end/tests/request_response_with_payload.c
@@ -136,21 +136,26 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -158,6 +163,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -173,10 +179,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -188,16 +196,19 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
index d678e7b..ac02b63 100644
--- a/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
+++ b/test/core/end2end/tests/request_response_with_payload_and_call_creds.c
@@ -208,21 +208,26 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -230,6 +235,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -252,10 +258,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -267,16 +275,19 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
index a50ad6f..c8252c5 100644
--- a/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
+++ b/test/core/end2end/tests/request_response_with_trailing_metadata_and_payload.c
@@ -147,21 +147,26 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_c;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &response_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -169,6 +174,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -185,10 +191,12 @@
   op->data.send_initial_metadata.count = 2;
   op->data.send_initial_metadata.metadata = meta_s;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -200,10 +208,12 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = response_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 2;
@@ -211,6 +221,7 @@
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_with_compressed_payload.c b/test/core/end2end/tests/request_with_compressed_payload.c
index 69fb70c..feb0d96 100644
--- a/test/core/end2end/tests/request_with_compressed_payload.c
+++ b/test/core/end2end/tests/request_with_compressed_payload.c
@@ -161,17 +161,21 @@
     op->data.send_initial_metadata.count = 0;
   }
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = send_flags_bitmask;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -179,6 +183,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -194,10 +199,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -209,12 +216,14 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_with_flags.c b/test/core/end2end/tests/request_with_flags.c
index 2863de7..e97ae89 100644
--- a/test/core/end2end/tests/request_with_flags.c
+++ b/test/core/end2end/tests/request_with_flags.c
@@ -136,17 +136,21 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -154,6 +158,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = flags_for_op[op->op];
+  op->reserved = NULL;
   op++;
   expectation = call_start_batch_expected_result;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
diff --git a/test/core/end2end/tests/request_with_large_metadata.c b/test/core/end2end/tests/request_with_large_metadata.c
index 2690784..53f7c45 100644
--- a/test/core/end2end/tests/request_with_large_metadata.c
+++ b/test/core/end2end/tests/request_with_large_metadata.c
@@ -144,17 +144,21 @@
   op->data.send_initial_metadata.count = 1;
   op->data.send_initial_metadata.metadata = &meta;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -162,6 +166,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -177,10 +182,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -192,12 +199,14 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/request_with_payload.c b/test/core/end2end/tests/request_with_payload.c
index 6fe96e1..fd237f4 100644
--- a/test/core/end2end/tests/request_with_payload.c
+++ b/test/core/end2end/tests/request_with_payload.c
@@ -135,17 +135,21 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_MESSAGE;
   op->data.send_message = request_payload;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -153,6 +157,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -167,10 +172,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_MESSAGE;
   op->data.recv_message = &request_payload_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -182,12 +189,14 @@
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_OK;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(103), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/server_finishes_request.c b/test/core/end2end/tests/server_finishes_request.c
index 3111925..406bea3 100644
--- a/test/core/end2end/tests/server_finishes_request.c
+++ b/test/core/end2end/tests/server_finishes_request.c
@@ -130,10 +130,12 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -141,6 +143,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -156,16 +159,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/simple_delayed_request.c b/test/core/end2end/tests/simple_delayed_request.c
index 750b734..0228c67 100644
--- a/test/core/end2end/tests/simple_delayed_request.c
+++ b/test/core/end2end/tests/simple_delayed_request.c
@@ -122,13 +122,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -136,6 +139,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -153,16 +157,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/simple_request.c b/test/core/end2end/tests/simple_request.c
index e66c9f2..ecfae08 100644
--- a/test/core/end2end/tests/simple_request.c
+++ b/test/core/end2end/tests/simple_request.c
@@ -130,13 +130,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -144,6 +147,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -159,16 +163,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
diff --git a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
index bdbca86..b30ec67 100644
--- a/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
+++ b/test/core/end2end/tests/simple_request_with_high_initial_sequence_number.c
@@ -130,13 +130,16 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_INITIAL_METADATA;
   op->data.recv_initial_metadata = &initial_metadata_recv;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
   op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv;
@@ -144,6 +147,7 @@
   op->data.recv_status_on_client.status_details = &details;
   op->data.recv_status_on_client.status_details_capacity = &details_capacity;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(c, ops, op - ops, tag(1), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);
@@ -159,16 +163,19 @@
   op->op = GRPC_OP_SEND_INITIAL_METADATA;
   op->data.send_initial_metadata.count = 0;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
   op->data.send_status_from_server.trailing_metadata_count = 0;
   op->data.send_status_from_server.status = GRPC_STATUS_UNIMPLEMENTED;
   op->data.send_status_from_server.status_details = "xyz";
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   op->op = GRPC_OP_RECV_CLOSE_ON_SERVER;
   op->data.recv_close_on_server.cancelled = &was_cancelled;
   op->flags = 0;
+  op->reserved = NULL;
   op++;
   error = grpc_call_start_batch(s, ops, op - ops, tag(102), NULL);
   GPR_ASSERT(GRPC_CALL_OK == error);