Resources are accessed in conflicting order on separate transactions, causing a deadlock. For example:
Transaction1 updates Table1.Row1, while Transaction2 updates Table2.Row2.
Transaction1 tries to update Table2.Row2 but is blocked because Transaction2 has not yet committed.
Transaction2 now tries to update Table1.Row1 but is blocked because Transaction1 has not committed.
A deadlock occurs because Transaction1 is waiting for Transaction2 to complete, but Transaction2 is waiting for Transaction1 to complete.
The system will detect this deadlock and will choose one of the transactions involved as a 'victim' and will issue this message, rolling back the victim's transaction.
Execute the transaction again. You can also revise the application to avoid deadlocks. The transaction that was chosen as a victim can be retried and will likely succeed, depending on what operations are being executed simultaneously.
To prevent or avoid deadlocks from occurring, consider having all transactions access rows in the same order (Table1, then Table2); this way, although blocking might occur, a deadlock will not occur.