5.4.2.4 Error Log Filtering

The --log-warnings option or log_warnings system variable controls warning logging to the error log. The default value is enabled (1). To disable warning logging, set --log-warnings or log_warnings to 0. If the value is greater than 1, aborted connections are written to the error log, and access-denied errors for new connection attempts are written. See Section B.4.2.11, “Communication Errors and Aborted Connections”.