While Joey’s solution should work, the issue seems to only be in the source code.
Perhaps this procedure is even better in this case:
- backup current mautic source somewhere on the server
- check the version of mautic, go to Mautic GH release page and download fresh source on to the server
- extract the source on the server
- put config and & media folders from backup to this fresh mautic source
- clear the cache
No need to install it on another server or re-run migrations.
Best, M.