EC
1229
MySQLERRORCommonLockingHIGH confidence

Lock wait timeout exceeded; try restarting transaction

Production Risk

High — frequent timeouts indicate lock contention requiring architectural review.

What this means

ER_LOCK_WAIT_TIMEOUT (1229, SQLSTATE HY000) — an alternate path to the lock wait timeout error — is raised when a transaction waits longer than innodb_lock_wait_timeout seconds to acquire a row lock. The waiting transaction is rolled back.

Why it happens
  1. 1Long-running transaction holding row locks that another transaction needs
  2. 2Application failing to commit or rollback transactions promptly
  3. 3Deadlock-adjacent scenario where one transaction is not automatically chosen as victim
How to reproduce
trigger — this will error
trigger — this will error
-- Session 1: holds lock
START TRANSACTION;
UPDATE accounts SET balance = 200 WHERE id = 1;

-- Session 2: waits and times out
START TRANSACTION;
UPDATE accounts SET balance = 300 WHERE id = 1;  -- waits... ERROR 1229

expected output

ERROR 1229 (HY000): Lock wait timeout exceeded; try restarting transaction

Fix

Identify and terminate blocking transaction

Identify and terminate blocking transaction
SELECT * FROM information_schema.INNODB_TRX;
KILL <blocking_thread_id>;

Why this works

Find the blocking transaction and kill it to release the lock.

Sources
Official documentation ↗

MySQL 8.0 — 1229 ER_LOCK_WAIT_TIMEOUT

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