EC
1547
MySQLERRORNotableEventsHIGH confidence

Failed to alter event

Production Risk

Low — the event is not modified; verify the event name.

What this means

ER_EVENT_CANT_ALTER (1547, SQLSTATE HY000) is raised when ALTER EVENT fails, typically due to the event not existing or storage errors.

Why it happens
  1. 1Event does not exist (use ER_EVENT_DOES_NOT_EXIST 1546 instead)
  2. 2Storage error while updating the event in mysql.event
How to reproduce
trigger — this will error
trigger — this will error
ALTER EVENT nonexistent_event ON SCHEDULE EVERY 2 HOUR;

expected output

ERROR 1547 (HY000): Failed to alter event 'nonexistent_event'

Fix

Verify the event exists before altering

Verify the event exists before altering
SHOW EVENTS LIKE 'my_event';

-- Then alter:
ALTER EVENT my_event ON SCHEDULE EVERY 2 HOUR;

Why this works

Verify the event exists with SHOW EVENTS before attempting to alter it.

Sources
Official documentation ↗

MySQL 8.0 — 1547 ER_EVENT_CANT_ALTER

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