Inside an address table is for example an email field
EMAIL VARCHAR 80 Charset ISO8859_1 Collate ISO8859_1

now convert the ODS Version 11.1 to 11.2 (Firebird 2.5)

The index after conversion will by inactiv.

OK Drop the index and create a new index.....

CREATE INDEX EMAIL_U ON ADDRESS COMPUTED BY (UPPER (EMAIL COLLATE ISO8859_1));

Cannot commit transaction:
Unsuccessful execution caused by an unavailable resource.
Implementation limit exceeded.
key size exceeds implementation restriction for index "ADDRESS_EMAIL_U".

If you change the Collate to DE_DE for the EMAIL field
and create the index like:
CREATE INDEX EMAIL_U ON ADDRESS COMPUTED BY (UPPER (EMAIL COLLATE DE_DE));

is will work fine.

Under firebird 2.1 is all OK.

Waht is the problem ?