Hello,
I often got this error when I try to restore a backed-up gdb:
"Attempt to store duplicate value (visible to active transactions) in
unique index "RDB$INDEX_11""
When I look at RDB$INDICES I can see that RDB$INDEX_11 is an unique
key for the field RDB$GENERATOR_NAME in RDB$GENERATORS. When I look
at the values in RDB$GENERATORS.RDB$GENERATOR_NAME I cannot find a
double entry.
Any ideas?

Win32, Firebird RC2

Regards,
Tilo Muetze