To save you the trouble of editing the wp-config.php file, you can use the plugin WP Debugging.((This and other 3rd-party plugins are not officially supported. Use at your own risk.)) After installation, go to the plugin screen under the Tools menu and select “Set WP_DEBUG to true”.
The plugin also lets you install the Debug Bar plugin that adds a menu entry “Debug Quick Look” where you can see the debug messages.
Identify messages from Tag Groups
The Tag Groups plugin adds its own messages that appear in the debug.log file prepended by
[Tag Groups] or
[Tag Groups Premium].
By default these messages inform you only about serious issues. If you turn on verbose logging, however, you will also receive details about deprecated shortcodes, caching, locale settings that cannot be provided by the operating system, processing of meta etc.. This information can help you understand what is going on under the hood.
Activate verbose logging on the page Troubleshooting -> Debugging
or add to wp-config.php:
define( 'CM_DEBUG', 'verbose' );
The additional messages will also appear in the file debug.log and can be viewed with the Debug Bar plugin.