Screen doesn't unlock; stuck on "Checking"

I'm also affected by this bug ! The only way I've found to work around this bug is to modify gnome-power-manager settings using gconf and untick options related to asking password after suspend or hibernation.

There is several instances of "gnome-screensaver" running when this bug occurs.
When the screen is stuck on "checking..." you can verify this by logging in in a different tty (with ctrl+alt+F1 or F2, etc...) and try ::
pstree -p | grep "screen"

(-p is for having PID needed to kill the process)

Here you can see that you have several instance of "gnome-screensaver" running. Now, you just have to kill one of screensaver by :
sudo kill #PID

and go to tty7 with ctrl + alt + F7

Does anybody know why several gnome-screensaver are running ?

I usually see this happen if my ecryptfs home directory has somehow become unmounted...
There's an outstanding bug in Sudo 1.8.2 which causes this (and is due to be fixed in 1.8.3), see Debian bug #639391.

Status changed to 'Confirmed' because the bug affects multiple users.

Best way I have found to switch back to your user it to use the "Switch User" button in gnome-screensaver, and use GDM to get back in.

If you prefer terminal, "killall gnome-screensaver" is much faster than finding the PID of the process and killing that.

I just got fed up enough to quit using it altogether, I log out now instead.

This is still an issue for me on 15.04. I have to alt-f1, log in and kill gnome-screensaver. Then I need to save everything and reboot because every few seconds the screen will turn black after doing this.

I don't use ecryptfs, I don't have several copies of gnome-screensaver running when this happens, and it's not a hibernation issue with me because it happens from a simple screensaver lock timeout - my music remains playing in the background.

It occurs about once per 30 or so screensaver locks, and usually Chrome is the only major thing I have open when my screen locks.

Yes I do have same issue, is there any way to get rid of it

Having this issue as well on 15.10.

Partial fix: After killing gnome-screensaver from a TTY, I've found that running:

    gnome-screensaver-command -a

activates the screen saver, but once unlocked, eliminates the screen-blanking problem that Tony Maro described.

Will also try "gnome-screensaver-command -d" instead of killing gnome-screensaver next time it happens to see if it works better.

Thanks for that tip Michael. Sad, but after updating to 16.04 the problem persists. I can't seem to find a permanent fix.

I've also changed video cards (nvidia 960 now) so the vid card itself apparently wasn't involved. This is an upgrade install all the way from 12.04 if I remember correctly, so I wonder if it's a leftover setting of some sort that's screwing it up.

The other possibility for me that is different is I use LDAP authentication (using sssd now, but previously directly with ldap and pam) so I wonder if it's something in the underlying authentication system and gnome 3 that causes it. I'm the only person in the organization running Gnome 3, everyone else is on Unity and doesn't experience it.

Actually one more comment - I was digging into my auth.log and it may be video related. The logs when it failed to unlock and when it succeeds are identical. I then noticed that one of my three monitors shows garbage at the bottom when I tap the top left corner to bring up the app chooser view in Gnome 3.

It makes me wonder if the screensaver isn't authenticating you properly, then just failing to go away...

Logs on a successful unlock and on a failure look identical:

May 17 10:31:46 river gnome-screensaver-dialog: pam_unix(gnome-screensaver:auth): authentication failure; logname= uid=1000 euid=1000 tty=:0.0 ruser= rhost= user=tony
May 17 10:31:47 river gnome-screensaver-dialog: pam_sss(gnome-screensaver:auth): authentication success; logname= uid=1000 euid=1000 tty=:0.0 ruser= rhost= user=tony
May 17 10:31:47 river gnome-screensaver-dialog: gkr-pam: unlocked login keyring

I'm using ordinary password authentication here. This system has also been through multiple upgrades, but I haven't upgraded to 16.04 yet. I run Gnome 3 on another machine without this problem (but I probably get that password right more often).

Let me know if there is anything I can look up or test on this machine to help.

I had never experienced this bug before until now, on 16.04 and Gnome 3. Every time I suspend the computer i get start in 'checking' when I try to log in back again.