While running "apt-get upgrade". Firefox crashed making the PC hanging. After pressing force-reset to reboot PC, I can't run "apt-get upgrade"
$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree... Done
The following packages have been kept back:
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
Running "sudo dpkg --configure -a" and "sudo apt-get update" did not help. Please advise how to fix the problem. TIA