I'm having this issue, but to be honest I'd never seen this error all the time I've been using aternos, but this time I'm using mods, the issue is when I try log into the server, this error appeared, the version of forge on the server and the launcher its the sema 1.16.5(36.2.39). I was checking the register, and it seems that the issue is a mod. The mod that its showing up like that its better animals, but I dunno if this is the actual problem Here's my latest log
I was checking the forum, just if by any chance someone had the same problem, so someone said to get into this page, load the latest log, then paste the link, so I'm gonna do it, maybe it can help Analysis of the latest log