'Dedicated server unabled to start'

Maybe your save file got corrupted. Is it possible to click on the rollbacks?

I also have this problem since 2 days ago, everything before was fine, now i can only run worlds without caves. After searching in google, i found several posts with same problems since 2016 - no good solution so far... I doubt this is something on our side, since i reinstalled game like 5 times and on second try it worked and i could start server with caves one time, after that it was impossible. My guess is something went wrong in game folders or steam.

I've had something similar happen - I've been unable to launch an 800+ day server.  It also says that's it's at day 1 below the title. :/  Really frustrating.