EC
1705
MySQLERRORCommonInnoDBHIGH confidence

Foreign key cascade depth exceeded maximum limit

Production Risk

High — DELETE or UPDATE fails mid-cascade; partial changes may be rolled back.

What this means

InnoDB limits the depth of cascading foreign key actions to 15 levels. Exceeding this limit causes the DML statement to fail.

Why it happens
  1. 1Deep chains of ON DELETE CASCADE or ON UPDATE CASCADE across many related tables.
  2. 2Circular or deeply nested FK relationships.
How to reproduce
trigger — this will error
trigger — this will error
-- Deleting from a root table that cascades through 16+ levels.

expected output

ERROR 1705 (HY000): Foreign key cascade delete/update exceeds max depth of 15.

Fix

Refactor the schema to reduce cascade depth

Refactor the schema to reduce cascade depth
-- Replace deep cascades with application-level deletion logic:
-- Delete child records manually in reverse order before deleting the parent.

Why this works

Handling deletions in application code avoids the InnoDB cascade depth limit.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 1705 ER_FK_DEPTH_EXCEEDED

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