So far this has happened twice, and I saved the logs from both instances. When a player enters an End Portal, the server will kick everyone out, show as offline, and I need to manually run the STOP command in the console to get the server to shut down.
After the server is rebooted, I am able to enter the End Portal again without issue.

 Instance one:
https://hasteb.in/alitidiw.md

Instance two:
https://hasteb.in/fakuvedi.md

(Towards the end of the pastebin, is where the crash occurs)

I do not know if it is a plugin or not casuing this issue, and would like some guidance. Thank you!