Server wont start

[MoonClover]

So my plugins weren't working, and I assumed it was because I was on 1.17. So I decided to go back to 1.16.5, now the server wont start. Logs: https://pastebin.com/g0kkBTvB. Whenever I try to start the server it goes to offline but not hibernating, and if I try to restart it it says "An unknown error occurred". Help please.

[_Tarna_]

Once you update to 1.17, you can't downgrade back to 1.16.5 without using a backup or resetting the world. That's why it tells you to make a backup whenever updating You can also just switch the server back to 1.17 for the server to start again. 

[MoonClover]

3 hours ago, _Tarna_ said:

Once you update to 1.17, you can't downgrade back to 1.16.5 without using a backup or resetting the world. That's why it tells you to make a backup whenever updating You can also just switch the server back to 1.17 for the server to start again. 

Okay, thanks!