The plugin could not open its required filter tables during initialization, stopping MySQL from loading the plugin.
MySQL error 3204 ER_PLUGIN_FAILED_TO_OPEN_TABLES appears when a plugin such as firewall or audit_log cannot read its filter tables in the mysql schema. Run mysql_upgrade, recreate missing tables, or reinstall the plugin to restore normal startup.
ER_PLUGIN_FAILED_TO_OPEN_TABLES
Error 3204 surfaces when a MySQL plugin cannot read or create the filter tables it needs inside the mysql system database. The server writes “Failed to open the %s filter tables” and refuses to activate the plugin.
The failure halts plugin features such as query auditing, firewall protection, or data masking, so fixing it quickly is critical for security and compliance.
Missing or corrupted mysql.firewall_* or audit_* tables stop the plugin from opening them at startup. Incorrect permissions on those tables or the entire mysql schema also trigger the issue.
Version mismatches after upgrades can leave the plugin expecting columns that do not exist. Finally, an incomplete uninstall or disk corruption can damage table metadata, blocking access.
First, verify table existence with SHOW TABLES IN mysql LIKE 'firewall%'; If they are missing, run mysql_upgrade or execute the plugin’s install script to recreate them.
If tables exist, check permissions: the mysql.sys or root user must have SELECT, INSERT, UPDATE, and DELETE. Grant access with GRANT ALL ON mysql.firewall_users TO 'mysql.sys'@'localhost'; then FLUSH PRIVILEGES.
When corruption is suspected, dump the mysql schema, drop the affected tables, and reload them from a healthy instance or the plugin installer.
After an in-place upgrade to 8.0, firewall tables built for 5.7 remain. Running mysql_upgrade upgrades their structure and resolves the error.
On fresh installs, administrators sometimes copy data directories without the plugin’s tables. Reinstalling the plugin with INSTALL PLUGIN firewall SONAME 'libmysqlfirewall.so'; rebuilds the tables automatically.
Always run mysql_upgrade after version upgrades to align system tables and plugin metadata.
Keep full backups of the mysql schema so you can quickly restore missing plugin tables.
Automate permissions checks in deployment pipelines to ensure the plugin’s service account retains access.
ER_PLUGIN_IS_NOT_LOADED warns that the server could not load the specified plugin library. Fix by installing or enabling the plugin.
ER_TABLEACCESS_DENIED_ERROR signals inadequate privileges on the plugin tables. Grant required rights to resolve.
The mysql.firewall_rules or audit_log_filter tables were never created or were dropped by mistake.
The plugin’s execution user lacks SELECT or INSERT on the filter tables, blocking access.
Upgrading MySQL without running mysql_upgrade leaves plugin tables at an older structure.
Disk errors or improper shutdowns damage the .frm or .ibd files, making them unreadable.
The plugin shared library could not be found or loaded.
Authentication plugin failed during initialization due to missing dependencies.
User does not have privileges to access the mysql system tables.
The server encountered an issue while installing the plugin, often due to incorrect file paths.
No, the server starts but the affected plugin is disabled, potentially exposing the instance to risk.
Only drop them if you have a backup or can reinstall the plugin immediately after; otherwise you may lose configuration data.
mysql_upgrade preserves data but updates system table structures; always back up before running it in production.
Galaxy’s schema-aware editor flags missing system tables during development and provides AI-generated remediation steps before changes reach production.
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