I started to have issues with my Mailwizz. At some point, I was no longer able to even create and test a campaign. I would get Error 400 every time I would try to set up a campaign. Here's the screenshot of the error: Then, I went to the backend to check the delivery logs and ran into another error, now 500 this time. Here's the screenshot: I did some research and found here the suggestion to clear the cache. I went to var/www/mymailwizz/apps/common/runtime/cache and ran rm on all files. Then, I rebooted the server and after some time went to my mailwizz page only to find out that it's no longer working. Then, I went to the server and enabled debugging in apps/init.php. Upon my check, I've got a page with errors detailed in my followup reply in this thread.