Unknown collation 🐬 MySQL

MySQL ERROR 1273 (HY000): Unknown collation: 'utf8mb4_0900_ai_ci'

A dump from MySQL 8 uses a collation the target server (MySQL 5.7 / MariaDB) doesn’t support.

Seen on: MySQL

Meaning

utf8mb4_0900_ai_ci exists only in MySQL 8. Importing into MariaDB or older MySQL fails.

Common causes

  • Dump created on MySQL 8, imported to MariaDB/MySQL 5.7
  • Hosting provider running an older MariaDB than your local MySQL 8

⚡ Quick fix

  1. Replace the collation in the dump with utf8mb4_unicode_ci
  2. Use the same server version on both ends

Detailed fix by platform

Linux

  1. sed -i 's/utf8mb4_0900_ai_ci/utf8mb4_unicode_ci/g' dump.sql

How to diagnose

  1. Versions — Source vs target server
  2. Recent change — Did it start after a deploy, upgrade, or configuration change? Compare with the last working version.

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