suspend is not working after updating to Ubuntu 14.04 from 13.10

Solution 1:

You're possibly seeing this bug: Black screen after login from suspend in Xubuntu 14.04. Try removing light-locker and light-locker-settings and installing xscreensaver to solve the issue of buggy suspend/resume.

Solution 2:

I have this problem after I used a different kernel version yesterday. Although I still don't know why it occurs, the following way may help you fix the problem.

To debug this problem is to run pm-suspend from terminal and check if there's something wrong by analyzing /var/log/pm-suspend.log.

For my case, a program which exit abnormal stopped the suspending. After I removed it, the suspend works again.

Running hook /etc/pm/sleep.d/soxy suspend suspend: 
Stopping Soxy proxy on port 7070       
No running Soxy process found
/etc/pm/sleep.d/soxy suspend suspend: Returned exit code 1.

Thu Sep 10 21:39:11 CST 2015: Inhibit found, will not perform suspend
Thu Sep 10 21:39:11 CST 2015: Running hooks for resume