Optional logging class com.mysql.jdbc.log.Log4JLogger was not included in the source/binary package for 5.1.14.

5.1.15 will ship with an SLF4J logger (which can then be plugged into Log4J). Unfortunately, it is not possible to ship a direct Log4J integration because the GPL is not compatible with Log4J's license. (Bug #59511, Bug #11766408)

The hard-coded list of reserved words in Connector/J was not updated to reflect the list of reserved words in MySQL Server 5.5. (Bug #59224)

MySqlProcedure accepted null arguments as parameters, however the JDBC meta data did not indicate that. (Bug #38367, Bug #11749186)

Using Connector/J to connect from a z/OS machine to a MySQL Server failed when the database name to connect to was included in the connection URL. This was because the name was sent in z/OS default platform encoding, but the MySQL Server expected Latin1.

It should be noted that when connecting from systems that do not use Latin1 as the default platform encoding, the following connection string options can be useful: passwordCharacterEncoding=ASCII and characterEncoding=ASCII. (Bug #18086, Bug #11745647)