Exception in server tick loop-Minecraft server does not start?

I changed my server version to the Spigot 1.8.8! However, my server no longer starts! This error message is coming:

Exception in server tick loop

Thanks in advance for your help!

Here is the crash report:

Maybe it's a plugin. My tip: Take down a plugin and see if it works. If not on it and with the next one. It's mostly plugins so I think you should try it out.

Thank you! I'll try it! I will contact you again c

Hey It's me again! The PLugins were not, but the worlds of the old version! I deleted it and Voila: It works!

Do you see! Just try it out.