Log in as admin Navigate to Development > Debugging in site administration Turn Debug messages up to the max (Developer) Open browser tools console, execute the following: require(['core/log'], log => {log.trace('trace'); log.debug('debug'); log.info('info'); log.warn('warn'); log.error('error');}) Confirm you see all trace/debug/info/warn/error messages in console output Set Debug messages to none Run the same command in your browser tools console Confirm you see only warn/error messages in console output