Thanx for the reply. Yes, maybe it fails only with ssh, not by other ways of syncing.
I did'nt try other syncing ways so far, and in fact I hesitate to use Dropbox because of some sensible data in my org-files.
Need to set up encryption before.
BTW:
The Stack trace after crashing says, a ClassNotFoundException was raised by not finding class 'org.ietf.jgss.Oid' on the path.
And, interestingly, the first entry in the searched path is "/data/app/com.matburt.mobileorg-1/base.apk".
I wonder about the trailing "...-1", like a non-clean deinstall and reinstall (which I did in my desparation...).
If this reminds you of something helpful, please let me know!