Unless this is somehow an old crash report, I'm not sure why it would hang up in this situation.
It's worked flawlessly since last update, but when I install DiscordConnect and try to do a server shut down or restart it saves world data and then hangs up. Without DiscordConnect it works as expected and as before.
I submitted the bug report to DiscordConnect and was sent your way over the hang up and crash. Logs are all posted here AMereBagatelle/DiscordConnect#1

You have version 1.1.0+1.15.2 installed on the server. Can you update to the newest version and look if this still occurs? The error message seems to be the same as from the last crash.

it's definitely 1.1.2+ 1.15.2
Must be an old log, I'll clear them entirely and update in a sec

Woops I'm stupid, that was from the 5th LOL