Learn more about this change here.
For help regarding Aternos, we recommend you to visit our support center.
Because the owner of this mod didn't make version for your forge version (maybe he just abandoned it)
What is the mod you are trying to install?
and what is your server version?
Try again of not working maybe error from curseforge
You are currently currently unable to install any mods and a lot of plugins, because curseforge blocked aternos(propably by accident). The Team is trying to contact curseforge and fix this problem. This only effects installing new mod and plugins.
Yes, it could be.
Then i just wait, no?
just wait until CurseForge unblock aternos
