I tried to export a layout set.
I choosed "Export" from the action context menu.
I've choosen "include related content.."
Download the file to .configarchive
In the target system, I've choosen
"Import" from the action context menu.
But then, I'll receive the error message
"Error while trying to process the import: Cannot run an import in the current configuration status "ReadOnly".
But I am Admin-User.