1. The user failed to carry out any database operations within a certain period of time, but was holding locks which other users were waiting for.
2. the database instance was in a deadlock situation.
A deadlock situation is where two or more users hold locks and request further locks that are held by the other users. In the simplest case of two users, one user holds one lock at least and requests another lock. But this lock is held by another user who is himself waiting for the lock held by the first user. This situation can only be resolved if one of the users releases the lock already obtained.
In some cases, the error message contains a more detailed description of the error.
In both cases, the lock requests must be checked and modified, if necessary. Repeat the last transaction.