Are you getting a crash error like this http://prntscr.com/kajc56 when you start your server?
There could be multiple reasons why this is happening and we will help you fix it.
1st, check if the message in console says "Out of Memory: True" - if it is true that means you are out of RAM and will need to upgrade to more.
2nd, if it is false on out of RAM, please go to File Management -> Crash Reports. If you have a Crash report that looks similar to this: https://prnt.sc/kaj9y9 - your fix most likely is the following:
- Redownload and upload your Jar from GetBukkit or Yive's Mirror etc. and make sure it is named correctly.
- If the above does not work, it is likely your worlds, go to File Management, then delete all your worlds. If you are still having trouble with this then please contact us and give us the server ID and crash report(s).
3rd, if your server is still not working, most likely it is an error with your mod(s), plugin(s) or config(s) such as spigot.yml, bukkit.yml etc. Make sure your configs are fine and look for any errors in console about any mods or plugins not being able to load. If no staff are online to help, consider trouble shooting by removing mods/plugins one by one and restarting every time you remove a mod/plugin or consider googling the solution. If staff are online, contact them.
4th, if your server is showing errors like this: http://prntscr.com/mimxoz -- it means that your JAR is corrupt and will need to be redownloaded and uploaded.