According to the documentation, startup disk creator will create Ubuntu startup disks. It seems to look for the Ubuntu tag in the disk type, and if you try to make a Debian disk, it will fail with that error message "Invalid version string 'GNU/LINUX'". This is the type for a Debian ISO, but not for Ubuntu.
My solution is to use UNetBootin, especially for non-Ubuntu disks.
According to the documentation, startup disk creator will create Ubuntu startup disks. It seems to look for the Ubuntu tag in the disk type, and if you try to make a Debian disk, it will fail with that error message "Invalid version string 'GNU/LINUX'". This is the type for a Debian ISO, but not for Ubuntu.
My solution is to use UNetBootin, especially for non-Ubuntu disks.