Fatal error: Uncaught Error: substr(): Argument #1 ($string) must be of type string, int given
in /usr/www/users/lffooxbydf/wp-content/plugins/wp-rocket/inc/ThirdParty/Plugins/CDN/Cloudflare.php on line 496

Call stack:

1. substr()
   wp-content/plugins/wp-rocket/inc/ThirdParty/Plugins/CDN/Cloudflare.php:496
2. WP_Rocket\T\P\C\Cloudflare::unregister_callback()
   wp-content/plugins/wp-rocket/inc/ThirdParty/Plugins/CDN/Cloudflare.php:469
3. WP_Rocket\T\P\C\Cloudflare::unregister_cloudflare_clean_on_post()
   wp-includes/class-wp-hook.php:353
4. WP_Hook::apply_filters()
   wp-includes/class-wp-hook.php:377
5. WP_Hook::do_action()
   wp-includes/plugin.php:523
6. do_action()
   wp-settings.php:779
7. require_once()
   wp-config.php:93
8. require_once()
   wp-load.php:50
9. require_once()
   wp-blog-header.php:13
10. require()
    index.php:17