PHP error guide

SQLSTATE 40001 deadlock found: meaning and fix

error sqlstate Affects: PDO with MySQL/MariaDB; exact server wording varies Last verified:

Error summary

Acquire resources in consistent order and retry the complete transaction with bounded backoff. InnoDB chooses this transaction as a deadlock victim to break a lock cycle.

What it means

Acquire resources in consistent order and retry the complete transaction with bounded backoff. InnoDB chooses this transaction as a deadlock victim to break a lock cycle.

What the error means

This message means that InnoDB chooses this transaction as a deadlock victim to break a lock cycle. The exact signature distinguishes sqlstate 40001 deadlock found from a generic application failure.

Why PHP produces it

The engine or service reports “SQLSTATE 40001 deadlock found” because its required precondition was not met. Acquire resources in consistent order and retry the complete transaction with bounded backoff.

PHP version notes

The sqlstate 40001 deadlock found wording here is based on PDO with MySQL/MariaDB; exact server wording varies; punctuation and exception class names can differ on older branches or vendor builds.

Most common causes

  • The immediate input or configuration reaches the specific condition: InnoDB chooses this transaction as a deadlock victim to break a lock cycle
  • The code path assumes the prerequisite for sqlstate 40001 deadlock found has already been satisfied.
  • For sqlstate 40001 deadlock found, development and production differ in version, extension, permissions, paths, or service configuration.
  • An earlier operation returned an unchecked value that is consumed by the line reporting sqlstate 40001 deadlock found.

Minimal examples

BAD — reproduces the problem

php 
$pdo->beginTransaction();
updateB(); updateA();

FIXED — safer pattern

php 
$pdo->beginTransaction();
updateA(); updateB();
$pdo->commit();

Step-by-step diagnosis

  1. Copy the complete “SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction” text and retain the first application stack frame.
  2. Reproduce sqlstate 40001 deadlock found in the same SAPI and environment listed for this page.
  3. Before changing sqlstate 40001 deadlock found, inspect the preceding value or directive and verify its type, path, version, and permissions.
  4. Apply the narrow correction—acquire resources in consistent order and retry the complete transaction with bounded backoff—then repeat the original request once.

Fixes

Correct the failing prerequisite

Acquire resources in consistent order and retry the complete transaction with bounded backoff

php 
$pdo->beginTransaction();
updateA(); updateB();
$pdo->commit();

Fail explicitly at the boundary

Validate the condition before the operation that emits sqlstate 40001 deadlock found, and log a safe diagnostic without credentials or full production paths.

Common mistakes when fixing it

  • Suppressing sqlstate 40001 deadlock found instead of correcting its upstream condition.
  • Testing sqlstate 40001 deadlock found only with the CLI binary when the failing request runs under FPM or Apache.
  • Changing a global setting for sqlstate 40001 deadlock found before confirming the site-specific effective configuration.

How to prevent it

  • Add a focused test that exercises the boundary responsible for sqlstate 40001 deadlock found.
  • Keep runtime versions, extensions, configuration, and deploy artifacts affecting sqlstate 40001 deadlock found reproducible.
  • Validate external data and service return values before they can trigger sqlstate 40001 deadlock found.

Web server / environment notes

fpm, cli, docker, linux. The failure occurs where innoDB chooses this transaction as a deadlock victim to break a lock cycle

Tags: fpm,cli,docker,linux

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