Before migrating to a new version, all Klocwork servers need to be stopped. If you fail to stop the services properly (for example, if the mySQL process was killed manually), migration fails. This error is indicated by the following:

Before migration, projects_root/logs/database.log does not end with "shutdown complete" line;
When running kwservice -r projects_root start --migrate, the mySQL server crashes when attempting to start. (On Windows, a dialog pops up and asks you to close the application);

After migration, your database log contains the following:

...
2015-08-28 11:40:13 8156 [Note] InnoDB: Database was not shutdown normally!
2015-08-28 11:40:13 8156 [Note] InnoDB: Starting crash recovery.
2015-08-28 11:40:13 8156 [Note] InnoDB: Reading tablespace information from the .ibd files...
2015-08-28 11:40:27 8156 [Note] InnoDB: Restoring possible half-written data pages
2015-08-28 11:40:27 8156 [Note] InnoDB: from the doublewrite buffer...
15:40:28 UTC - mysqld got exception 0xc0000005 ;
This could be because you hit a bug. It is also possible that this binary
...
... crash ...

To resolve these issues, start your old server for the relevant projects_root, ensure all services are stopped and then continue your migration to the latest version.