Issue #12039 - Update the http.server.rst with the requirement to call `end_headers` after calling `send_header`.
diff --git a/Doc/library/http.server.rst b/Doc/library/http.server.rst
index d9539f7..e77e81d 100644
--- a/Doc/library/http.server.rst
+++ b/Doc/library/http.server.rst
@@ -188,9 +188,10 @@
.. method:: send_header(keyword, value)
Adds the HTTP header to an internal buffer which will be written to the
- output stream when either :meth:`end_headers` or :meth:`flush_headers`
- is invoked. *keyword* should specify the header keyword, with *value*
- specifying its value.
+ output stream when either :meth:`end_headers` or :meth:`flush_headers` is
+ invoked. *keyword* should specify the header keyword, with *value*
+ specifying its value. Note that, after the send_header calls are done,
+ :meth:`end_headers` MUST BE called in order to complete the operation.
.. versionchanged:: 3.2 Storing the headers in an internal buffer