I attempted to upgrade our 6.0.3 CLM installation to 6.0.4 RC1 and ran into the following errors when upgrading the Jazz Team Server (this eror was reported in repotools-jts_addTables)

CRJAZ1431E The model "COMPONENT_ID_IDX" was illegally changed to be unique.
CRJAZ1431E The model "CHANGE_SET_ID_IDX" was illegally changed to be unique.
CRJAZ1430E  Detected one or more illegal model evolutions during migration.  See above for details.  No changes were made to your database.
...
CRJAZ1791E The migration completed with errors. The imported database is unstable and should not be used without further analysis.

My 6.0.3 environment is used for performing ISO 26262 tool qualification of the CLM tool and successfully completed tests just prior to attempting this upgrade.  While I do have backups and can restore the 6.0.3 environment (i.e. I have not 'lost' anything) I would be interested in knowing if this error is 'to be expected' with RC1 (I observed, and expected, this problem with the Milestone builds - but had expected the upgrade process to work properly for RC1 so the error..occurring on the very first application..was a surprise to me).