Planned Order Release - Exception Handling - ORA-01422, ORA-06512

When some of our schedulers tried to release planned orders (discrete - make), they got the following error in 12.1.3.9:

Error in the release process. Please check the setup.

ORA-01422: exact fetch returns more than requested number of rows

ORA-06512: at "APPS.MRP_AP_REL_PLAN_PUB", line 2435

ORA-06512: at "APPS.MSC_REL_PLAN_PUB", line 1036

When checked, the package body of 'MRP_AP_REL_PLAN_PUB' at line 2433 TO 2436 reads as:

2433   EXCEPTION

2434      WHEN NO_DATA_FOUND THEN NULL;

2435      WHEN OTHERS THEN RAISE;

2436   END;

RAISE what?

The exception is raised when the code tries to submit 'WIP Mass Load'.

Since it is an Exception, we assume it is a data issue. But we are not much informed or educated through this exception handling message.