Install button in the software center is grayed out when trying to install .debs without an internet connection [closed]
Solution 1:
Try installing from the command line:
gdebi-gtk /full/path/to/deb/file
Solution 2:
Gdebi package manager is removed from default application set and unfortunately softwarecentre also stopped offline installation support from Oneric (but install option in the menu may still work) so you have to use command line for offline installation.
try this
dpkg -i filename.deb