Fix UTF-8 Issue with Special Characters
If you use specific language characters on your site (such as Č, Ć, Š, ä, ö, ü, ß…) and these look broken after activating WP Rocket, there is an issue with UTF-8 encoding on your site.
To solve the issue, add this at the top of your wp-config.php, just after
ini_set( 'default_charset', 'UTF-8' );
Finally, clear WP Rocket’s cache once.