Version: origins-forge-1.20.1-1.10.0.5-all.jar
Forge: 47.2.20

I've been having this error pop up in my multiplayer server, causing us to be unable to join the server. It would take a few tries before I'm able to join again. I'm unsure about what's going on here.

For reference, I do have Medieval Origins Revival installed as well. I'm not sure if that could also lead to issues.

If you could, please see if the issue persists with:

• just Medieval Origins Revival and Origins Forge, and required dependencies
• keeping your existing mod list but removing Medieval Origins Revival

As well, please send the latest.log file from your logs folder after receiving the error.

This is an issue with our registry system, and I'm unsure if it's fixable due to us having to work around Forge's registry system to make reloadable datapackable registries a thing.

Potentially in future versions of the mod when we make a jump to NeoForge, we'll rewrite this system to be more in line with vanilla registries, and it should be fixed there.

I've managed to fix it by removing a line that removes the key from the registries map, and handling concurrency so content isn't missing.