Nextcloud has been working fine for months.
The auto updater failed in trying to unlink (delete?) files.
A ‘clean’ installations of the new files, plus the original config.php allowed the cli upgrade to proceed with no apparent errors.
From previously working clients, using fstab entries:
your-site/nextcloud/remote.php/dav/files/nextcloud-user/ /media/mount-point davfs _netdev,user,rw,noauto 0 0
/sbin/mount.davfs: mounting failed; the server does not support WebDAV
Clients can connect using this method:
mount -t davfs https://your_site/owncloud/remote.php/webdav /home/$YOUR_USER/owncloud
Also, the password entry timeout is crazily short, at approx 5 seconds!!!
I wouldn’t have upgraded had I realised that it wasn’t ready for production yet. 
