I logged into Virtualmin today and saw a Virtual Server called 136326768332378. It was enabled for Mail only, but no Users added. No domain was added for it. I did not add this, dont know where it came from.
So I deleted it. After deleting it I got this message:-
Virtualmin has detected that 9 domains on your system are configured to allow symbolic links to other users' files. This can be exploited by a domain owner to access configurations files and private data in other virtual servers.
WARNING : Fixing this setting will break all virtual servers that have content or applications under symbolic links to other directories.
Although, I also ran yum update earlier, so maybe this error was due to package updates. The Virtual Server was there before package updates.
After fixing it, it said it needed to fix .htaccess issues. I did this and one of my sites sub-domains reported an internal server error 500.