monitors.xml settings from the display applet can make gnome unusable on next login

[Mark A. Hershberger]

I was trying to switch the "primary" monitor for Ubuntu and after some back-n-forth, both monitors went blank.

Switched to a text console, restarted gdm and after logging in the monitors both went blank.

Upgraded everything and got the same problem.

Finally managed to get firefox up with a minimal .xinitrc and found https://wiki.ubuntu.com/X/Config/Resolution which told me to look at ~/.config/monitors.xml. I edited the file in emacs (from which I have the original, buggy monitors.xml~ file) and managed to get a working session.

Looking at the diffs, I'm not sure *why* the buggy setup blanked both monitors and I haven't logged in again with what I think is the bad monitors.xml to confirm it.

I'll submit this bug and my monitors.xml + diff and then try to verify that the monitors.xml that I think causes the problems actually does. BBIAS ;)

[Mark A. Hershberger (hexmode)]

diffs that there are in the bad monitors.xml

[Mark A. Hershberger (hexmode)]

Ok, that diff doesn't produce the bad monitors.xml. I'll have to try later to reproduce the problem.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "tmp.diff" of this bug report has been identified as being a patch. The ubuntu-reviewers team has been subscribed to the bug report so that they can review the patch. In the event that this is in fact not a patch you can resolve this situation by removing the tag 'patch' from the bug report and editing the attachment so that it is not flagged as a patch. Additionally, if you are member of the ubuntu-reviewers team please also unsubscribe the team from this bug report.

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[Mark A. Hershberger (hexmode)]

Ok, I've managed to reproduce this problem and have a monitors.xml that reliably produces it for me.

The 1366x768 configuration for my laptop does not seem to work when I have a 1920x1200 monitor attached. When the 1920 monitor is attached, the laptop works when it is set to 1360x768. I'm not sure what the difference is other than those 6 rows of pixels.

I have it hooked up to a 1280x1024 external monitor right now and the 1366 resolution doesn't seem to cause a problem. Memory issues?

[Mark A. Hershberger (hexmode)]

Attaching a configuration I just tested. It works until I log in and then fails. After I hit "super-p" or some other key combo to get switch monitor configs, it becomes somewhat usable. In this case, I've edited monitors.xml so that the primary monitor in the config to be the external monitor.

Note that although the LCD shows as active here, nothing is displayed on it.

[Mark A. Hershberger (hexmode)]

Ok, the 1366 mode is causing problems no matter what external monitor is attached. I think it does it more reliably fails with the larger external screen.

Switching the last monitors.xml to 1360 seems to allow it to work.

[Launchpad Janitor (janitor)]

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

[NoOp (glgxg)]

Affects me on 12.04 and 13.04. The only way I've found to 'fix' the problem is to delete ~/.config/monitors.xml.