<p>This error appears when the mysql.ndb_replication system table does not match the schema expected by the NDB storage engine, blocking replication and cluster operations.</p>
<p>MySQL Error 1625 ER_NDB_REPLICATION_SCHEMA_ERROR signals that the mysql.ndb_replication table has an invalid structure. Recreate or upgrade the table to the correct schema with an ALTER or DROP/CREATE statement to restore NDB replication functionality.</p>
ER_NDB_REPLICATION_SCHEMA_ERROR
The server raises this error when it detects that the mysql.ndb_replication metadata table is missing, corrupted, or structured differently from what the running NDB version expects.
The check happens during NDB engine start or when replication statements refer to mysql.ndb_replication. Any mismatch prevents replication metadata from loading and halts NDB-based replication.
Cluster replication metadata is stored in mysql.ndb_replication. If column names, data types, or indexes differ, NDB cannot reliably map server IDs and epoch information, so it aborts to protect data consistency.
The cluster will still start, but replication to other NDB clusters or MySQL instances is disabled until the schema is corrected. Leaving it unresolved risks data divergence and failed failovers.
Upgrading the mysqld binary but skipping mysql_upgrade leaves mysql.ndb_replication in the old format.
Someone altered or dropped columns in mysql.ndb_replication while experimenting with replication settings.
Restoring user databases without the mysql system schema omits the required ndb_replication table.
Changing the table engine from NDB to InnoDB breaks the expected metadata layout.
Raised when any mysql.* system table is missing.
Appears if a system column type is wrong after a failed ALTER.
Blocks DDL changes including system table repairs in read-only mode.
No full downtime is required; you only need write access to the mysql schema. Applications can stay online, but replication will remain paused until fixed.
No. It only adjusts system tables. User data stays untouched.
You can, but future upgrades may fail, and the warning will reappear. It is safer to correct the schema.
Galaxy flags failed DDL statements in real time, letting you detect and repair system table issues quickly from its SQL editor.
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