vitessio/vitess · error

mysqld >= 8.0.21 required to disable the redo log

Error message

mysqld >= 8.0.21 required to disable the redo log

What it means

ProcessCanDisableRedoLog queries MySQL to check whether the server supports disabling the InnoDB redo log (introduced in MySQL 8.0.21, via innodb_disable_redo_log). If the SELECT returns no rows, the MySQL version is too old to support the variable, so this error is thrown to signal the feature is unavailable. It is a capability gate, not an operational failure.

Source

Thrown at go/vt/mysqlctl/redo_log.go:41

func (mysqld *Mysqld) DisableRedoLog(ctx context.Context) error {
	return mysqld.ExecuteSuperQuery(ctx, "ALTER INSTANCE DISABLE INNODB REDO_LOG")
}

func (mysqld *Mysqld) EnableRedoLog(ctx context.Context) error {
	return mysqld.ExecuteSuperQuery(ctx, "ALTER INSTANCE ENABLE INNODB REDO_LOG")
}

func (mysqld *Mysqld) ProcessCanDisableRedoLog(ctx context.Context) (bool, error) {
	qr, err := mysqld.FetchSuperQuery(ctx, "SELECT variable_value FROM performance_schema.global_status WHERE variable_name = 'innodb_redo_log_enabled'")
	if err != nil {
		// It's possible that the MySQL process can disable redo logging, but
		// we were unable to connect in order to verify. Let's assume not and
		// let the caller decide if they want to retry.
		return false, err
	}
	if len(qr.Rows) == 0 {
		return false, errors.New("mysqld >= 8.0.21 required to disable the redo log")
	}
	return true, nil
}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Upgrade mysqld to MySQL 8.0.21 or later so the redo-log disable capability variable exists.
2. If upgrading is not possible, skip the redo-log-disabling code path (don't attempt it on older servers).
3. Add a preflight version check (mysqlctl.ParseVersionString) before attempting to disable the redo log and log a clear skip message.

Example fix

// before
// assumes redo log can be disabled on any MySQL
canDisable, err := mysqld.ProcessCanDisableRedoLog(ctx)

// after
// gate on version first
version, _ := mysqld.GetVersionString()
if mysqlctl.ParseVersionString(version).Major >= 8 && mysqlctl.ParseVersionString(version).Minor == 0 && mysqlctl.ParseVersionString(version).Patch >= 21 {
    canDisable, err = mysqld.ProcessCanDisableRedoLog(ctx)
} else {
    log.Info("mysqld < 8.0.21, skipping redo log disable")
}

version, err := mysqld.GetVersionString(ctx)
if err != nil { return err }
v := mysqlctl.ParseVersionString(version)
canDisableRedoLog := v.Major > 8 || (v.Major == 8 && (v.Minor > 0 || v.Patch >= 21))
if !canDisableRedoLog {
    log.Info("mysqld < 8.0.21; redo log cannot be disabled")
}

canDisable, err := mysqld.ProcessCanDisableRedoLog(ctx)
if err != nil {
    if strings.Contains(err.Error(), "8.0.21") {
        log.Info("redo log disable unsupported on this mysqld; continuing")
    } else {
        return vterrors.Wrapf(err, "checking redo log capability")
    }
}

When it happens

Trigger: Calling ProcessCanDisableRedoLog against a mysqld instance older than 8.0.21: the query for the redo-log capability variable succeeds but returns an empty result set (len(qr.Rows) == 0), causing errors.New("mysqld >= 8.0.21 required to disable the redo log").

Common situations: Running backups or fast-restores with redo-log disabling (e.g. during restore to speed up data loading) against a MySQL 5.7 or MySQL 8.0.x (< 8.0.21) install; environments pinned to older MySQL builds such as Percona distributions lacking the feature.

Related errors

• running MySQL version %q is newer than backup MySQL version
• running MySQL version %q is older than backup MySQL version
• running MySQL version %q is too new for backup MySQL version
• cannot determine database flavor details for version %s
• cannot use backup between different flavors: %q vs. %q

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/9b6f8e4446a390d5. Report an issue: GitHub.