OsakaSora

I created a server with the Pixelmon mod, it's fine and everything but a person enters and the server closes, I don't know how to explain it very well but I attach the detailed file of the error that happens to me https://mclo.gs/eSemvtq This error had not happened to me until now, so I don't understand very well why this happens, could you help me solve it?

When I create the server and log in it lets me play, but a person ends up joining and it sends me an error and the server closes The report says Exception in server tick Loop I put here what the console tells me because I honestly don't know how to explain it: https://mclo.gs/eSemvtq I use Forge mods and this has not happened to me until now