Bug/Issue Dedicated Server Not Launching

I was running my own dedicated server (Linux) successfully for a month or so. I took it down briefly to add a user login to the server config file. The server would not start after I made my changes. I restored a backup version of the config file. Same problem.

Please don't just reply only with "post your server log" unless you actually think it is relevant. The very last entry in the log was that the server went down gracefully when I intentionally stopped it. Nothing gets added to the log when I try to start this up.

The error I get is a great big dump that starts as follows:
[Error] Fatal Exception caught: (StartException) Could not perform initial Root load

followed by a whole bunch of exceptions with hex codes. Any ideas on how to fix this, or where else to ask? I am crossposting to the subreddit and asking in the Discord linked in the subreddit.

Also, I should add: nothing is wrong with the universe files from the server or the player files. I copied them into my local install and everything works fine from there.

 

Two images: one of what I get when I try to launch, and my most recent log.
https://imgur.com/a/Jg21rEq