I use Ubuntu 15.04, I have a SSD drive also. Very recently onwards the ubuntu is taking long to shut down nearly 1:30 minutes.
I checked the shutdown log messages and I get the follow message.
A stop job is running for Session c2 of user ***** (25s/ 1min 30 s)
It count downs till 1:30 minutes and then shutdown the machine.
Why is it happening.
