@gette Delete forge-client.toml and try again
@ToxicGold180 Your issue is completely unrelated and doesn't even involve a supported version, please update and make your own thread to receive support.
Please don't necro old threads.
The backup process is there for a reason and we don't add an option to disable it because we have seen people shoot themselves in the foot before.
Any mod could do that, you could even do it with the command you're using to get the info.
Find out what mod is responsible for the method by which you obtained the diamond that is not like a diamond spawned with /give
Please provide debug.logs from both server and kicked client, using one of the paste sites listed in the "Logs" section of my signature below, just expand the spoilers.