Hey there @tithenon 
Sorry to hear that you’ve run into some issues with v11 update. We do generally wait a while before recommending the update to a new version, just to give modules a chance to catch up and for any bugs that do surface to be addressed.
That said, it should be possible to get everything back up to speed. First, you will need to decide if you want to stick with v11 and smooth it out, or whether you want to go back to v10.
Option A: Stick with v11
If you want to stick with v11, switch your Foundry server version to v11.299, and then go to the Bazaar and make sure to update your modules and systems to v11 versions. Torg does have a v11 compatible release on the Bazaar here (but you’ll only see it if your Foundry version is set to v11).
Then, go to the game configuration screen and use the Import Wizard to import the backup you made before switching to v11. This will be a v10 backup, and we will attempt to re-migrate it to v11. Make sure that you launch your world in safe configuration to eliminate modules and module versions as variables.
If that works, you’re set to continue and start enabling modules again. Otherwise: Option B.
Option B: Rollback to v10
Switch your Foundry server version to v10.291 (v10.291 is the most stable and recent of the v10 versions, so I do recommend switching to that instead, but you can use v10.288 instead if you like).
Then, go to the Bazaar and make sure to update your modules and systems to v10 versions instead of v11 versions.
After that, Then, go to the game configuration screen and use the Import Wizard to import the backup you made before switching to v11. Now, make sure that you launch your world in safe configuration to eliminate modules and module versions as variables.
This should do the trick. If you think that the pre-v11 backup you have might not be working, I recommend taking a look at Save Points. We may have a backup of your v10 world even if you were not on World Builder tier at the time since we take daily backups for all users.
With both Option A and Option B, make sure you look at your dev tools console (F12 in your browser when you start up the world) and your Foundry Server logs (on game configuration screen, see image) for signs of what might be going wrong.
Hope this helps you out! If you’re running into issues restoring the backup, please do shout! And if you see any specific errors in the logs that might tell us why the world is not starting up, please post them as screenshots 