**Before filling out this issue: **
1. For major bugs, we only support BYG's latest version on a per Minecraft version basis(i.e latest for 1.15 is 1.0 while latest for 1.16 is 1.1).
2. Please test BYG on its own to confirm whether or not this is a mod conflict

Mod conflict? If so, please clarify which mod is conflicting, if not skip this.

API/Modloader
Forge/Fabric?

Describe the bug
What is the bug? Where/How does it occur? etc.

To Reproduce
Please provide step by step instructions

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots/Videos
If applicable, add screenshots/video to help explain your problem.

Additional context
Add any other context about the problem here.

Logs
Use: https://paste.ee/ and paste the links. if log is huge please upload those
Please provide:
Crashlog -
Debug.log -
Latest.log -

Heap Dumps
If performance, please provide a heap dump/some sort of profile of your game(I recommend: https://visualvm.github.io/download.html)
Heap Dump/Profile -

Sounds like a registry mismatch.
Your client and server probably have different mods installed, check to see if this is the case.

Most definitely a registry mismatch which is typically caused when the server and client are not using the same version of the mod.