Created attachment 811453 [details]
multiple-btrfs-yast-error.png

Affected version: Tumbleweed [Build 20190723] 

Steps to reproduce:

1. Start installation of Tumbleweed (Build 20190723) for system with at least 2 disks;
2. Proceed to Expert Partitioner Step;
3. Format any disk with Btrfs and mount to "/";
4. Select "Btrfs" in System View;
5. Select "Modify" -> "Change Used Devices...";
6. Click "Remove All" button to move recently formatted btrfs partition back to Available Devices list.

Expected result:
The device is moved to "Available Devices" list. No errors occurred.
Actual result:
Internal error occurred. Please see "multiple-btrfs-yast-error.png" screenshot and y2logs for the details.