Learn more about this change here.
For help regarding Aternos, we recommend you to visit our support center.
I can still run it xD
I cant open too when i change it to 1,12 from 1.13
I think it's because of the world version though. If you switch from 1.13 to 1.12, most of the blocks (kelp, fishes, etc.) will remain unknown in 1.12
1.13 cannot be used on Aternos, no matter what software is used.
And, since it essentially crashes your server upon trying to start it, even after switching back to 1.12 I think, then 1.13 essentially "corrupts" your server, making it never start unless Reinstalled.
1) 1.13 is known to be very bad in performance. We already increased the available resources for 1.13 servers.
2) 1.13 uses a new world format. Worlds from older minecraft versions are converted while playing. This decreases the performance more and more.
You can try to start your server with force upgrade mode enabled. Your world gets completely converted into the new format while your server is starting. This might help to increase the performance a bit.
3) The new world format can only be read by 1.13 and newer versions. So if you try to start your server in e.g. 1.12 with a 1.13 world or a world which has been used 1.13 once, your world will be broken.
This is why we recommend to create a backup before switching from an older version to 1.13.
Unfortunately we do not have any influence on that. However we try to get the best out of it.
I cant open too when i change it to 1,12 from 1.13
see 3)
