Whenever I use deployers and activate them with no use just yet (etc. to mine cobblestone or grab items), it crashes my game and the world is lost forever.

This issue has been marked as stale because it has been inactive for 3 weeks. It will be closed if it remains inactive for another 3 weeks.

This issue has been closed since it has been inactive for 3 weeks since it was marked as stale.

I have the same problem, I can even give detailed information on how it happens.
Deployers with a solid block with 1 block in between will crash the game. Since they can't be stopped after the crash, the crash will just continue until fixed. It breaks a lot of farms and in general is a gamebreaking bug. I will attach a screenshot giving the position in which they will corrupt a file.

If the right pair would get powered (1 block gap between deployer and bedrock) it will ultimately result in a crash.

I hope it gets fixed soon, had to take all my farms down.

I had the exact same problem and got essentially banned from my server because of it. I was using forge 1.16.3-forge-34.1.0 with create-mc1.16.5_v03.1a

I just installed forge 1.16.5 and I had no issues with the deployers, leading me to believe that the issue is with forge 1.16.3 and create 1.16.5 together

If the crash report says the error is a ticking block entity then there is a forge setting (remove erroring tile entities) that you can TEMPORARILY enable to automatically remove the block causing the error, thus recovering the world.

I just installed forge 1.16.5

Does it affect other mods that use 1.16.3?

If the crash report says the error is a ticking block entity then there is a forge setting (remove erroring tile entities) that you can TEMPORARILY enable to automatically remove the block causing the error, thus recovering the world.

I tested this and it does work, thank you for the help