ORA-20002, Error '-21525 while compiling flexfields

Sadiq reported this error today:

While compiling the flexfields, the procedure wf_event.raise failed with following

parameters:

event_name = oracle.apps.fnd.flex.dff.compiled

event_key = FND.$SRS$.FNDSCARU

The error raised is:

ORA-20002: 3825: Error '-21525 - ORA-21525: attribute number or (collection element at index) violated its constraints' encountered during execution of Rule function 'fnd_bes_proc.process_event' for event 'oracle.apps.fnd.flex.dff.compiled' with key 'FND.$SRS$.FNDSCARU'.

There is a similar error described in Metalink Note 430477.1 which suggests applying patch 5625612 (which is superseded by ATG_PF.H RUP5 which is again superseded by RUP6). However this patch was already applied in the instance where the above error occurred.

This was solved by increasing the open_cursors in init.ora reportedly.