Incompatible Change: The parser accepted statements that contained /* ... */ that were not properly closed with */, such as SELECT 1 /* + 2. Statements that contain unclosed /*-comments now are rejected with a syntax error.

This fix has the potential to cause incompatibilities. Because of Bug#26302, which caused the trailing */ to be truncated from comments in views, stored routines, triggers, and events, it is possible that objects of those types may have been stored with definitions that now will be rejected as syntactically invalid. Such objects should be dropped and re-created so that their definitions do not contain truncated comments. If a stored object definition contains only a single statement (does not use a BEGIN ... END block) and contains a comment within the statement, the comment should be moved to follow the statement or the object should be rewritten to use a BEGIN ... END block. For example, this statement:

CREATE PROCEDURE p() SELECT 1 /* my comment */ ;

Can be rewritten in either of these ways:

CREATE PROCEDURE p() SELECT 1; /* my comment */
CREATE PROCEDURE p() BEGIN SELECT 1 /* my comment */ ; END;

(Bug#28779)

Incompatible Change: The file mysqld.exe was mistakenly included in binary distributions between MySQL 5.0.42 and 5.0.48. You should use mysqld-nt.exe. (Bug#32197)

Incompatible Change: Multiple-table DELETE statements containing ambiguous aliases could have unintended side effects such as deleting rows from the wrong table. Example:

DELETE FROM t1 AS a2 USING t1 AS a1 INNER JOIN t2 AS a2;

This fix enables alias declarations to be made only in the table_references part. Elsewhere in the statement, alias references are allowed but not alias declarations. However, this patch was reverted in MySQL 5.0.54 because it changed the behavior of a General Availability MySQL release. (Bug#30234)

See also Bug#27525.