MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6

5.4.2.4 Error Log Filtering

The log_error_verbosity system variable controls server verbosity for writing error, warning, and note messages to the error log. Permitted values are 1 (errors only), 2 (errors and warnings), 3 (errors, warnings, and notes), with a default of 3. If the value is greater than 2, the server logs aborted connections and access-denied errors for new connection attempts. See Section B.4.2.10, “Communication Errors and Aborted Connections”.