Comment # 42 on bug 1131752 from Stefan Dirsch

[ 31463.805] (II) AIGLX: Suspending AIGLX clients for VT switch
[ 31470.512] (II) AIGLX: Resuming AIGLX clients after VT switch
[ 31470.533] (EE) modeset(0): failed to set mode: Invalid argument
[ 31470.533] (EE) 
Fatal server error:
[ 31470.533] (EE) EnterVT failed for screen 0
[ 31470.533] (EE) 
[ 31470.534] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
[ 31470.534] (EE) Please also check the log file at "/var/log/Xorg.0.log" for
additional information.
[ 31470.534] (EE) 
[ 31470.536] (II) AIGLX: Suspending AIGLX clients for VT switch
[ 31470.604] (EE) Server terminated with error (1). Closing log file.


[31470.484756] systemd[1]: Starting Backup RPM database...
[31470.488935] systemd[1]: Starting Load/Save RF Kill Switch Status...
[31470.505947] systemd[1]: check-battery.service: Succeeded.
[31470.506282] systemd[1]: Started Check if mainboard battery is Ok.
[31470.511829] systemd[1]: Started Load/Save RF Kill Switch Status.
[31470.538024] systemd[1]: snapper-timeline.service: Succeeded.
[31470.544145] PM: hibernation exit
[31470.545118] systemd-sleep[20283]: System resumed.

Hmm. I don't seem to find anything obvious in dmesg here. :-(