unattended-upgrades doesn't complete plinth upgrade on first try

I ran unattended-upgrades in the background, and after a while it wasn't running anymore, and plinth had also stopped running.

This was at the end of /var/log/unattended-upgrades/unattended-upgrades-dpkg.log:

Preparing to unpack .../29-plinth_0.10.0-1_all.deb ...

So it looks like unattended-upgrades stops plinth, but doesn't manage to complete the upgrade. When I run it a second time with unattended-upgrades -v from the command line, I get this:

dpkg: error processing package plinth (--configure):
 package is in a very bad inconsistent state; you should
 reinstall it before attempting configuration
cp: cannot stat '/etc/modprobe.d/*': No such file or directory
Errors were encountered while processing:
 plinth

But anyway it completes the upgrade, and plinth is running again at this point.