Databases created in pre-Beta builds of Firebird 5.0 may be inaccessible in the Release Candidate 1 release and have to be recreated.ODS was changed a few times during the development cycle and the Firebird Project generally does not guarantee ODS being stable before the Beta stage.

RC1 has an ODS change affecting the profiler, specifically with nullability and default values of its procedures and functions.If you intend to use (or have already used) the profiler, it is advisable to recreate the database.

Also, if you used the profiler in a pre-RC1 build, and don’t intend to recreate the database, you will need to drop the tables and views prefixed with PLG$PROF due to changes in these tables (which are not considered part of the ODS).The next use of the profiler will recreate these tables and views.

That said, you can copy the Firebird engine library from the Firebird 3.0 distribution package (named engine12.dll (Windows) and libEngine12.so (POSIX), and located inside the /plugins sub-directory) to continue working with databases in ODS 12 without needing a backup/restore.However, new features introduced with Firebird 4.0 and Firebird 5.0 will not be accessible.