40001: serialization_failure

What does it mean?

Under the SERIALIZABLE or REPEATABLE READ isolation level, the transaction could not be serialized because it conflicted with concurrent changes, and it was cancelled. This is expected behavior that protects data consistency.

Why does it happen?

Transactions accessing the same data concurrently cannot be arranged in a serializable order, write conflicts under high concurrency, or dangerous dependencies detected by SSI (Serializable Snapshot Isolation).

How to fix it

This is not a bug but an expected signal: retry the transaction as is. Add automatic retry logic to the application. To reduce conflicts, shorten transactions and use a lower isolation level (READ COMMITTED) if it is not really needed. Design to reduce contention on hot rows.