Ok, I uploaded my recently build website to the demo-server and did a dev/build.
Oops! Somehow, the entire server ran into it's memory limits, killing everything with it. Not my intention!
What went wrong:
Assets-folder didn't get the proper permissions for some reason!
This problem sometimes occures in a PureFTPD environment I noticed after some testing with my own sandbox.
So, when uploading a new site, it's always good to check if all the permissions are correct. This will save you a lot of trouble!
It's simple, almost stupid, but not checking and killing a VPS, does not make a happy hosting-company!