The world metadata file is damaged
What it looks like in your log
Exception reading ./world/level.dat
What causes it
level.dat, the file that describes the whole world, is corrupt or unreadable. The server may refuse to open the world.
How to fix it
Copy level.dat_old over level.dat inside the world folder (it is a seconds-older duplicate), or restore from a backup.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log