mkdir: /iOSSources: Read-only file system

When I'm trying to execute 

`./scripts/15-ConvertIosProject.sh
`

I get this error: 

> mkdir: /iOSSources: Read-only file system

And I can't seem to find a way to resolve it. 

Steps tried so far: 
- redo entire setup in a different location
- check settings / environment setup
- change permissions on the folders / files 

Nothing works. Please help. 