I was able to revert my server back to 242.9 by using Survival Server's ARK Backup feature (at the bottom of your control panel). That may be your best bet for now. Not sure if there are any risks with restoring to a backup, though, so keep that in mind since I have no clue.
Edit: Looks like I lost everything that wasn't on my person restoring a backup, haha. Thankfully I hadn't made much progress, but just be warned.