Digikam shared library error

["B.M." <b-misc@gmx.ch>]

Hi,

I've just upgraded two installations from jessie to stretch. Both have digikam 
installed. First installation runs digikam without any problem. But on the 
second one I've a shared library error:

Digikam: error while loading shared libraries: libgphoto2_port.so.10: cannot 
open shared object file: No such file or directory

Interestingly, on both systems synaptic says that digikam-private-libs depends 
on libgphoto-port12 (>=2.5.10) which is installed on both and no libgphoto-
port10 is installed on neither the machine with the running nor the one with 
the not-running digikam. How's that possible?

I already tried checks, reinstalls of digikam and its dependencies, cruft and 
so on but I don't find out, what the root of the problem really is. Any hints 
on how to solve that are welcome...

Thank you,
Bernd