Can't update nextcloud by using nc-update-nextcloud because of btrfs filesystem?

Hi I have a NC running on a thin cliend using a fresh Debian 7 and I want update to NC 16. Nowadays I have
Currently this is my test instance for nextcloud. So I installed the os and nextcloudpi on an fresh btrfs filesystem.
Problem is now, the nc-update-nextcloud script stops with the output “BTRFS not supported”. Is that real? I thought btrfs is the optimal filesystem for nextcloudpi to allow snapshots and subvolumes?

I would be pleased, if anyone can help me solve this problem.

Thank you for the help!!!