To sum things up, today I went to start my server and update it to 1.13. I made the recommended adjustments, like enabling Force Upgrade for my world, but upon loading in I kept my inventory (probably thanks to setting the gamerule previously) but the world was reset, and after 10 minutes the world forced me out again with the message "timed out" and requeueing does no help. On the server panel the server never said it was active, simply saying "starting..." before defaulting to Offline again.
The world is completely vanilla, no mods or plugins.
Any help or thoughts on this would be appreciated.