If you are using an Optimize Press plugin, then you might have encountered this notification error:

Notice: Use of undefined constant OP_SN - assumed 'OP_SN' in ... /wp-content/plugins/optimizePressPlugin/lib/framework.php on line 494

Notice: Use of undefined constant OP_SN - assumed 'OP_SN' in ... /wp-content/plugins/optimizePressPlugin/lib/framework.php on line 495

This happens if you your WordPress wp-config.php file debug is set to True. I first noticed this notification when my websites upgraded to 4.0 version, and it was very annoying to have this error appearing in the front end of your website.

The solution though is very simple. Just login to your cpanel, locat wp-config.php and look for this line:

 define( 'WP_DEBUG', true ); 

Simply change the “true” to “false”, then click save. That should take out that error line.

Do you have any other solution? Share it below.