How to fix bbPress error There has been a critical error on this.

How to fix this error users where getting when trying to login to the site that has bbPress installed.

There has been a critical error on this website. Please check your site admin email inbox for instructions. Learn more about troubleshooting WordPress.

You need to commented out this line from the the file
/wp-content/plugins/bbpress/includes/admin/classes/class-bbp-converter-db.php

// register_shutdown_function( array( $this, '__destruct' ) );
// 
// if ( WP_DEBUG && WP_DEBUG_DISPLAY ) {
//    $this->show_errors();
// }