At random, your server might not start and appear like it’s crashing, and if you look in your console and server log you will see this error: net.minecraft.server.WorldConlictException: Failed to check session lock, aborting
To fix this: 1. Stop your server.
2. Access your files and go into your main world’s folder.
3. Delete the session.lock file you see.
4. Start your server and it should start up with no issues.