OCTCR46A204001/KM000007410 documented a ZMF4ECL problem that was liable to occur when a user’s TSO password contained a special character. For example, a user whose password contained an ampersand (‘&’) character receives an 'ICH408I...INVALID PASSWORD GIVEN' response at logon time with a SER8210E message visible either alongside the ICH408I or in the ZMF Server started task output.

As stated in the above KB article, this problem was resolved in the ZMF4ECL 8.3 release and affected customers should upgrade to the latest available hotfix version of the ZMF4ECL 8.3 client software, which is compatible for use with all currently supported lower versions of the Server (i.e. mainframe) software.