When logging onto the multiplayer server I play on, I am immediately booted back to the Minecraft Launcher if I have any Resource Pack set.

Once logged on, I can set my Resource Pack back, but the pictures are set to Minecraft standard instead of what it should, and item frames are completely wrong and show the wrong item, if they show anything resembling an item.

Lastly, while riding on tracks, I was booted similarly to the log in issue, though I have not been able to repeat that error.