I agree, though I couldn't find one more appropriate.  EncoderNotAvailableException isn't right either.  The message for DateEncoderNotAvailableException ("There is no encoder for value [%s] of type %s") is fairly general.  Would you be okay with renaming this exception ValueEncoderNotAvailableException or some such, or should I make a new more specific one (or just use a generic DatabaseException)?