Next, I used a fresh Debian 8 for ArmoryQt. Still "hexit" errors.
Then I installed a fresh Debian 9 on a physical machine (instead of the VMs before). Just installed ArmoryQt, nothing else. And, again, scanning for a new wallet never ends in ArmoryQt, with "hexit" errors.
So it must be ArmoryDB after all?
Any ideas what to do? I did upgrade ArmoryDB before, no change. The last thing I didn't do yet is delete the ArmoryDB database?

Ente