If your having login problems and your character cannot be found you need to update your DB as follows.
Get SDB 0.5.2rev272:
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In the newest mangos rev go in the sql folder, then updates. Execute all sql files after 2578 on the mangos database, except the 2606_realmd_account.sql which you execute on the realmd database.
This will update your SDB to the latest version that is required for the latest mangos (currently 2618).
I've verified myself that this fixes any "character not found" errors due to fields not being there or problems with character creation/spells.