Hey there, sad you’re having these issues. Mostly this is caused due to old cache files being stored on your
/wp-content/cache/ folder. So the first thing should be disable all cache (also the Varnish for that App on App Settings), also disable the Varnish Add-On on WP Rocket before disabling WP Rocket itself.
Then you have to go via SSH or SFTP and delete everything you may have on your
/wp-content/cache/ (I mean, everything there inside), and also if you have a
/wp-content/wp-rocket-config/ you should delete everything inside it, if there’s any.
When you start with WP Rocket, disable all Minification options, these should be the last to be applied, and one by one, testing everything and checking when and what breaks (they have pretty instructional tutorials right from inside the plugin dashboard, in case you don’t know). Remember to add all exclusions (URLs, Cookies, UserAgents) on the proper WP Rocket, it helps avoiding errors.
Just then you enable Varnish cache on the App Settings at the Cloudways Platform (add again all the URL and Cookie exclusions you’ve already added on WP Rocket), and then you enable the WP Rocket Varnish Add-On. Then back to the Cloudways Platform, go to your Server --> Manage Services and hit Purge on the Varnish at the bootom of the page.
Last but not least, then you copy your CDN URL into the proper WP Rocket field and save. Remember, mostly you can’t CDN all of your assets. You’ll have to try and test until you see your site is working. Takes some time and patience but once you get it, you got it! Remember to Purge Varnish again, and also on App Settings, Purge CDN Contents.
The most important, never activate all at once. First the “safe” thing (the ones you know won’t break), then one by one, testing (with caches off including WP Rocket Cache engine) and enabling one by one.
I hope it helps solving your issues. It’s common to have issues when migrating if you forget to disable and delete (via SFTP) all cache files, or also disconnecting some API’s from your WordPress before migrating… That’s why this is normally a paid service, but your 1st Site is migrated FOR FREE by Cloudways, and they can garantee you that nothing will be broken. Cheers!