This error means that something went wrong -- somewhere -- while OMGF’s API was instructed to generate a stylesheet. Due to the way WordPress’ was built, this could literally mean that any plugin at any point in time, before or after OMGF's API was invoked, caused either an error, warning or notice.
First, open your
wp-config.php file and make sure any of the following constants are set to false, or not set at all:
If any of these constants are set (e.g.
define('WP_DEBUG', true);) either remove the line or change
false. This will stop WordPress from attempting to print any notices or warnings in
text/html, effectively allowing OMGF to print its stylesheet in