After 8 hours (or however long your wait_timeout is set to), your app tries to execute a MySQL query and the connection has gone away. node-mysql throws the error: Can't add new command when ...

Jack Wallen explains how to add data into a MySQL table from the command line.

First, make sure your user account is set to use mysql_native_password. Otherwise, the connector will not connect. Second, MySQL user accounts include the user + host. If you grant access to me@<IP ...