Minecraft Version

1.20.1

What happened?

I have this mod installed both sides. It still complains about missing mod on server.

How do you trigger this bug?

1. Install this mod on server and client
2. Try connecting to the modded server with the modded client

Loader

Forge

Loader Version

47.3.12

API Version

No response

Mod Version

Elytra Slot 6.4.4+1.20.1

Relevant Log Outputs

[21:15:05] [Netty Client IO #4/ERROR]: Channels [elytraslot:main] rejected their server side version number
[21:15:05] [Netty Client IO #4/ERROR]: Terminating connection with server, mismatched mod list

Added more mods from singleplayer pack and it suddenly works... Could be a dependency problem.

Added more mods from singleplayer pack and it suddenly works... Could be a dependency problem.

Could you add more info about what those mods were? I'm having the same exact problem with the same version, Forge

Added more mods from singleplayer pack and it suddenly works... Could be a dependency problem.

Could you add more info about what those mods were? I'm having the same exact problem with the same version, Forge

Alright, I can confirm that indeed it's an issue of not having all of the mods installed.
When you can't connect to a server due to mismatching mod list, in the txt log file there is a list with "optional" mods that might or might not be needed by the client.
Those mods are usually needed for some reason and this solves the issue, however it's weird that Forge tells me that it's this mod's fault that I can't connect to the server. Maybe it's an issue with forge or whatever is giving me this error.

The described method solves this issue but, the weird behavior might be a sign that something's off in the mod's code I guess.