Thank you for the comments. So far everything has gone ok, I fixed all the fields with ASCII charset at the FB 2.54 DB (changed the domain to charset NONE), and now the backup and restore workes fine, with no errors.

I've noticed the new FB3 DB has now two SYSDBA users, one seems to be disabled, and the other has the masterkey password even though the install asked me for the password, but it appears it ignored my answer, or it used the password I entered for the disabled SYSDBA users... no big deal.

Other than that I have not encountered any other issues so far, I will recompile all stored procedures and views and triggers shortly, but I don't expect any issues there because the DB is operational with the Application and no errors have appeared on the APP side using the FB3 DB.

Cheers,

Fabian