I'm playing in a server right now and if I make a secret trap door, I will be able to use it for maybe 6 hours of server time before it causes the issue. The issue is any time I look at the trap door it crashes my game and if I try to join my server back I keep crashing because my character is still looking at the secret trap door. The only way I can evade it is by having a friend teleport me somewhere else before I load in with my character looking at the trap door.

If the server is public and is not set up to use that mod in itself, it will crash to prevent you from "cheating". If a server does not already have that mod built in, it will either attempt to ban you or something because players who DONT have the mod will see it differently than you do, like perhaps they couldnt walk through a ghost block. if your server is public and doesnt allow that mod i would suggest to stop, as you could get banned.

This is my own server

Is this with 1.1.2 or 1.16?

1.12

I know this is a late reply but its whatever xD

If the server is public and is not set up to use that mod in itself, it will crash to prevent you from "cheating". If a server does not already have that mod built in, it will either attempt to ban you or something because players who DONT have the mod will see it differently than you do, like perhaps they couldnt walk through a ghost block. if your server is public and doesnt allow that mod i would suggest to stop, as you could get banned.

Is this with 1.1.2 or 1.16?