How to enable debugging in phpBB3
If you are experiencing problems with your phpBB3 forum such as slow loading times, you may want to enable its debug mode. This way you will be able to see valuable information about your forum such as page loading time, number of queries executed, memory usage, etc.
To enable debugging in phpBB3, you need to open the config.php file located in the phpBB3 installation folder with a text editor. At the end of the file you will see these two lines:
// @define('DEBUG', true);
// @define('DEBUG_EXTRA', true);
Uncomment them by removing the // symbols in front of each line. The uncommented lines will look like this:
Save the changes in the file and reload your forum. At the bottom of each page you will see the debug information.