How to stop server from crashing while starting up

A friend and I have been playing ATM 7 to the sky together on an Aternos server for about two weeks maybe. Most of the time it works great, and I don't recall any issues when the server is actually online, but sometimes it crashes on startup. Once or twice I've been able to get it online by just clicking start again after it crashed, but right now every time I press start it crashes before starting up completely. I've tried to load a previous backup; however, this didn't seem to help. Any help would be appreciated, thanks.