Can't log in using gdm3 [xf86OpenConsole: VT_ACTIVATE failed: Operation not permitted] but lightdm and sddm work fine

Thank you for taking the time to report this bug and helping to make Ubuntu better. It sounds like some part of the system has crashed. To help us find the cause of the crash please follow these steps:

1. Look in /var/crash for crash files and if found run:
    ubuntu-bug YOURFILE.crash
Then tell us the ID of the newly-created bug.

2. If step 1 failed then look at https://errors.ubuntu.com/user/ID where ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine. Do you find any links to recent problems on that page? If so then please send the links to us.

3. If step 2 also failed then apply the workaround from bug 994921, reboot, reproduce the crash, and retry step 1.

Please take care to avoid attaching .crash files to bugs as we are unable to process them as file attachments. It would also be a security risk for yourself.

Hello Daniel,

here you can find the link:

https://errors.ubuntu.com/user/a0bccc0d41c89b42afbe332929a7f00566720fe2fcfc8f4ca657778404328e77f704f6088efe855865488a2f9635243b26b54e543fe6e58c26f7de6c73d1df8c

Thanks,
Luca

On Mon, Aug 17, 2020 at 5:55 AM Daniel van Vugt <email address hidden>
wrote:

> Thank you for taking the time to report this bug and helping to make
> Ubuntu better. It sounds like some part of the system has crashed. To
> help us find the cause of the crash please follow these steps:
>
> 1. Look in /var/crash for crash files and if found run:
> ubuntu-bug YOURFILE.crash
> Then tell us the ID of the newly-created bug.
>
> 2. If step 1 failed then look at https://errors.ubuntu.com/user/ID where
> ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine.
> Do you find any links to recent problems on that page? If so then please
> send the links to us.
>
> 3. If step 2 also failed then apply the workaround from bug 994921,
> reboot, reproduce the crash, and retry step 1.
>
> Please take care to avoid attaching .crash files to bugs as we are
> unable to process them as file attachments. It would also be a security
> risk for yourself.
>
>
> ** Changed in: gdm3 (Ubuntu)
> Status: New => Incomplete
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1891771
>
> Title:
> gdm3 crashes after upgrade from bionic to focal but lightdm and sddm
> work fine
>
> Status in gdm3 package in Ubuntu:
> Incomplete
>
> Bug description:
> Hi all,
>
> after upgrading from bionic to focal I switched from lightdm to gdm3
> to use Gnome Desktop.
>
> Gdm3 crashes systematically when enabled as default display-manager
> with a blank display with the following message:
>
> Oh no! Something has gone wrong.
> A problem has occurred and the system can't recover. Please contact a
> system administrator.
>
> In /etc/gdm3/custom.conf I've tried the following settings:
>
> WaylandEnable=false -> crash
> WaylandEnable=true -> crash
>
> I've enabled Debug but I cannot find any correlation with the error
> message.
>
> Gdm version 3.34.1-1ubuntu1.
>
> Switching to another display manager like lightdm or sddm solves the
> problem.
> I've a Dell Inspiron with Intel U620 graphic card.
> The problems happens with the laptop display alone but also with
> external monitor connected via HDMI.
>
> Thanks in advance for your help.
>
> Regards
> Luca
> dpkg
>
> ProblemType: Bug
> DistroRelease: Ubuntu 20.04
> Package: gdm3 3.34.1-1ubuntu1
> ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
> Uname: Linux 5.4.0-42-generic x86_64
> ApportVersion: 2.20.11-0ubuntu27.6
> Architecture: amd64
> CasperMD5CheckResult: skip
> CurrentDesktop: ubuntu:GNOME
> Date: Sat Aug 15 23:06:37 2020
> InstallationDate: Installed on 2016-12-14 (1340 days ago)
> InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64
> (20160719)
> SourcePackage: gdm3
> UpgradeStatus: Upgraded to focal on 2020-08-11 (4 days ago)
> mtime.conffile..etc.gdm3.custom.conf: 2020-08-15T00:22:27.116452
>
> To manage notif...

Thanks. The crash then would be:

https://errors.ubuntu.com/oops/434241b4-de4d-11ea-af75-fa163ee63de6

which has no backtrace :(

And then this Xorg error occurs, which explains why you can't log in:

ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: (WW) xf86OpenConsole: VT_ACTIVATE failed: Operation not permitted
ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: (EE)
ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: Fatal server error:
ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: (EE) xf86OpenConsole: Switching VT failed
ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: (EE)
ago 14 18:43:07 vyger /usr/lib/gdm3/gdm-x-session[3755]: (EE)

The display manager is meant to provide that privilege (I think).