Rename utf8b error handler to surrogateescape.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 164f7e4..555dc12 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -245,7 +245,7 @@
 				return -1;
 
 			stringobj = PyUnicode_AsEncodedString(
-				u, Py_FileSystemDefaultEncoding, "utf8b");
+				u, Py_FileSystemDefaultEncoding, "surrogateescape");
 			Py_DECREF(u);
 			if (stringobj == NULL)
 				return -1;