I've been trying to install XnViewMP .deb on my Ubuntu system.
The result was this error as I tried to run 'sudo dpkg -i XnView_MP026_all.deb':
"error in Version string 'MP026': version number does not start with digit"
according to this forum https://answers.launchpad.net/launchpad ... on/147533/
"The policy has always been that way, but dpkg started enforcing it now."
To enforce installation I've used
sudo dpkg --force-all -i XnView_MP026_all.deb
but probably it would be better to fix that version number

Regards,
Ale