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LMDE 7 Upgrade: LightDM Configuration Fails on NVIDIA (RTX 4070) After Upgrade #72
Description
The upgrade path from LMDE 6 to LMDE 7 consistently results in a TTY1 Lockout on systems using modern NVIDIA proprietary drivers (series 550). The primary issue is a failure of the default Display Manager, LightDM, to initialize the graphical session after the kernel and drivers are installed.
System Information
Initial OS: Linux Mint Debian Edition 6 (LMDE 6)
Target OS: Linux Mint Debian Edition 7 (LMDE 7 'Gigi')
GPU: NVIDIA GeForce RTX 4070
Driver Version Used: nvidia-driver-550.163.01-2 (automatically installed during upgrade)
Steps Taken / Observed Failure
Ran mintupgrade from LMDE 6 to LMDE 7.
NVIDIA driver 550.x.x was installed and DKMS modules were built (confirmed via dkms status).
Upon reboot, the system failed to launch the graphical environment and consistently dropped to tty1 (text login) despite driver installation success.
Critical Workaround/Solution
The system was stabilized only after replacing the default display manager:
Logged into tty1.
Installed the alternative display manager: sudo apt install gdm3
Set GDM3 as the default when prompted.
Executed sudo reboot.
Conclusion: GDM3 successfully manages the NVIDIA driver initialization and starts the Cinnamon session on LMDE 7 where LightDM fails. This strongly suggests a compatibility or configuration error within the LightDM package or its interaction with the new Xorg configuration under LMDE 7.
Request
Please investigate the LightDM/NVIDIA configuration files during the upgrade path to prevent this TTY lockout for other NVIDIA users.
Activity
TheZupZup commentedon Oct 11, 2025
@clefebvre
leigh123linux commentedon Oct 11, 2025
This isn't a lightdm-settings issue, I suggest you look at your logs before assigning blame.
TheZupZup commentedon Oct 11, 2025
Thank you for reopening the issue.
I can confirm I am currently running a "fully stable LMDE 7 system" (with the Cinnamon desktop) ONLY because I replaced LightDM with GDM3.
The functional diagnosis is clear:
This conclusively proves the failure lies within LightDM's post-upgrade initialization with the NVIDIA driver, not the driver itself. Since the system is now stable, the need for logs is reduced, as the point of failure (LightDM) has been isolated and replaced.
TheZupZup commentedon Oct 11, 2025
oct 11 03:16:50 Zephir systemd[1]: Failed unmounting tmp.mount - Temporary Directory /tmp.
TheZupZup commentedon Oct 11, 2025
journalctl -b -1 | grep Xorg
oct 11 03:15:28 Zephir /usr/libexec/gdm-x-session[1681]: (--) Log file renamed from "/var/log/Xorg.pid-1681.log" to "/var/log/Xorg.0.log"
oct 11 03:15:28 Zephir /usr/libexec/gdm-x-session[1681]: (==) Log file: "/var/log/Xorg.0.log", Time: Sat Oct 11 03:15:28 2025
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.746:222): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=1681 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.746:223): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=1681 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.746:224): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=1681 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.746:225): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidia-modeset" pid=1681 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.750:226): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidiactl" pid=1681 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.754:227): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=1681 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.758:228): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=1681 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.758:229): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=1681 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.758:230): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidia-modeset" pid=1681 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:30 Zephir kernel: audit: type=1400 audit(1760166930.978:231): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidiactl" pid=1681 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:46 Zephir /usr/libexec/gdm-x-session[2490]: (--) Log file renamed from "/var/log/Xorg.pid-2490.log" to "/var/log/Xorg.1.log"
oct 11 03:15:46 Zephir /usr/libexec/gdm-x-session[2490]: (==) Log file: "/var/log/Xorg.1.log", Time: Sat Oct 11 03:15:46 2025
oct 11 03:15:46 Zephir kernel: audit: type=1400 audit(1760166946.518:270): apparmor="ALLOWED" operation="capable" class="cap" profile="Xorg" pid=2490 comm="Xorg" capability=12 capname="net_admin"
oct 11 03:15:46 Zephir kernel: audit: type=1400 audit(1760166946.518:271): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/etc/nvidia/current/nvidia-drm-outputclass.conf" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.518:272): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.518:273): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:255" pid=2490 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.518:274): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:255" pid=2490 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.518:275): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidiactl" pid=2490 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.526:276): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/2490/comm" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.526:277): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.526:278): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:0" pid=2490 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:47 Zephir kernel: audit: type=1400 audit(1760166947.526:279): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:0" pid=2490 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:15:54 Zephir kernel: audit: type=1400 audit(1760166954.614:404): apparmor="ALLOWED" operation="capable" class="cap" profile="Xorg" pid=2490 comm="Xorg" capability=2 capname="dac_read_search"
oct 11 03:15:56 Zephir kernel: audit: type=1400 audit(1760166956.666:405): apparmor="ALLOWED" operation="capable" class="cap" profile="Xorg" pid=2490 comm="Xorg" capability=2 capname="dac_read_search"
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.103:406): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.103:407): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=2490 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.103:408): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=2490 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.103:409): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidia-modeset" pid=2490 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.107:410): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/dev/nvidiactl" pid=2490 comm="Xorg" requested_mask="wr" denied_mask="wr" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.115:411): apparmor="ALLOWED" operation="open" class="file" profile="Xorg" name="/proc/driver/nvidia/params" pid=2490 comm="Xorg" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.115:412): apparmor="ALLOWED" operation="unlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=2490 comm="Xorg" requested_mask="d" denied_mask="d" fsuid=0 ouid=0
oct 11 03:15:57 Zephir kernel: audit: type=1400 audit(1760166957.115:413): apparmor="ALLOWED" operation="symlink" class="file" profile="Xorg" name="/dev/char/195:254" pid=2490 comm="Xorg" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
oct 11 03:16:09 Zephir kernel: audit: type=1400 audit(1760166969.764:439): apparmor="ALLOWED" operation="capable" class="cap" profile="Xorg" pid=2490 comm="Xorg" capability=2 capname="dac_read_search"
oct 11 03:16:42 Zephir kernel: audit: type=1400 audit(1760167002.620:440): apparmor="ALLOWED" operation="capable" class="cap" profile="Xorg" pid=2490 comm="Xorg" capability=2 capname="dac_read_search"
journalctl -b -1 -p err..alert | grep -i 'error|fail|denied|nvidia|lightdm'
oct 11 03:16:50 Zephir systemd[1]: Failed unmounting tmp.mount - Temporary Directory /tmp.
leigh123linux commentedon Oct 11, 2025
How is that useful? all it show is gdm (running on xorg) started, there isn't any mention of lightdm!
Look in /var/log/lightdm for the failures in it's logs.
leigh123linux commentedon Oct 11, 2025
You are wrong. the need for logs isn't reduced.
Just because gdm works doesn't mean much, FTR lightdm it provided by the Debian repo not LinuxMint, we only provide the lightdm greeter.
clefebvre commentedon Oct 14, 2025
Can we see a screenshot of the settings in lightdm-settings?
And the output of
TheZupZup commentedon Oct 14, 2025
Clem i just want to say that these setting i didn't touch any of those in those picture
clefebvre commentedon Oct 14, 2025
These look all OK.
clefebvre commentedon Oct 14, 2025
You might need to troubleshoot a bit to get to the bottom of this...
Maybe your Xorg.conf is outdated or you've got a mix of different versions of the NVIDIA drivers?
TheZupZup commentedon Oct 14, 2025
yes exactly my NVIDIA driver was overwrites i had the 535 before on LMDE 6 and the installation tried to overwrite it with the 550 driver on LMDE 7
Could that be the cause Clem ?
right now i'm not in front of my Linux LMDE 7 i will be at 17h00 pm in canada
leigh123linux commentedon Oct 14, 2025
Post the logs I requested earlier, they are all useful.
In fedora they are located in /var/log/lightdm/
10 remaining items
brunoherc commentedon Oct 15, 2025
Hibernation also results in a boot loop with no video... I guess I'll mark this as an unsuccessful upgrade and reinstall from scratch...
@TheZupZup do you have any similar issues?
brunoherc commentedon Oct 15, 2025
Ok, some updates:
sudo lightdmdoes open lightdm as expected;sudo lightdmon any kernel refuses to resume from suspend.mkey commentedon Oct 22, 2025
I have a very similar problem to what has been described above after upgrading to LMDE 7.
Noteworthy points
The current situation
startxPreviously attempted troubshooting steps
Freshly attempted troubleshooting steps
I have updated My current kernel command line (the first part is a workaround for suspending GPU RAM), but does not help the situation.
Logs seem to suggest my command line was not applied. Not sure why that is.
Here's a list of installed packages. I likely (?) dropped some packages when I uninstalled Lightdm in favor of Lxdm. Not sure why were they not reinstalled.
After installing lightdm-autologin-greeter & slick-greeter
Logs after installing above packages and a reboot.
lightdm-after-install.zip
I can notice this in the logs and can confirm that this path indeed does not exist.
Which lead me here: https://wiki.archlinux.org/title/LightDM#LightDM_does_not_appear_or_monitor_only_displays_TTY_output
I applied the setting (it was commented out) and rebooted once again, but that does not change anything.
lightdm-after-lightdm-setting.zip
I will also attach all the config files that appear related to Lightdm.
lightdm-config.zip
leigh123linux commentedon Oct 22, 2025
@mkey Try creating /usr/share/lightdm/lightdm.conf.d/50-minimum-vt.conf
and add
mkey commentedon Oct 22, 2025
Thanks, I'll give that a go later today and report back, I already compromised my daily duties with the unscheduled troubleshooting this morning :D
mkey commentedon Oct 22, 2025
OK, doing as you have suggested does change something. After reboot I get to a login screen (it first asked for the username two times and then finally I inputted the password). The login screen now asks for the username every time, I would expect it to ask only for the password while having the username stored.
After that I land on a black screen and after a good 30 second delay I get to the desktop.
The greeter has started showing up in the logs. The kernel options as I have specified in /etc/default/grub are not present during boot, even after running
update-grub.lightdm-minimum-vt.zip
The "30 second delay" is closer to 60 seconds, I'll have to time it, but now it's noticeably longer than before. Is something timing out, causing this delay?
I can't get the kernel parameters to apply through grub. I tried a few different combinations, but the kernel every time starts with the "quiet splash" default.
OK, I finally got it to apply, not sure which of the three options did it, likely the last one.
I can't get rid of "quiet splash" though, but that's completely ancillary to the issue at hand.
leigh123linux commentedon Oct 22, 2025
@mkey Try removing these packages
mkey commentedon Oct 22, 2025
I executed
sudo apt remove lightdm-autologin-greeter lightdm-gtk-greeterand also proceeded to remove
gir1.2-lightdm-1.I also ran
sudo dpkg-reconfigure lightdmfor good measure.After reboot, now I'm not getting that duplicate username box on the login screen. However, I get a login screen prompting me for a username, which I proceed to input.
After a few seconds the screen goes black and I'm again prompted for a username, my previous input having been cleared. After inputting it and the password, I get to see again the black screen with mouse pointer on it, and some 27 seconds later I get to the desktop.
lightdm-after-greeter-uninstall.zip
leigh123linux commentedon Oct 22, 2025
The double login issue is similar to an old fedora issue
ubuntu/lightdm#291
The fix is unreleased, master only
ubuntu/lightdm@f772b5e
mkey commentedon Oct 22, 2025
Hmh, I tried a few combos, not sure that I'm applying these correctly, but it's a no go.
I think probably the most important bit of information here is that for the first login this issue does not occur.
I'll likely give a try to a fresh install over the weekend and then see what's what. Thanks for the help.
justindemuro commentedon Oct 23, 2025
I'm having the same issue: lightdm failing to launch and dropping into TTY1 consistently on boot. Nvidia driver is 550.163.01. GPU is RTX2060. This is with a fresh install of LMDE 7 beta. Prior to installing the nvidia driver, (so it was using nouveau), lightdm would launch after booting without issue. So this only started happening after I installed the nvidia drivers.
My current workaround is to login at the TTY1 prompt, then run
sudo systemctl restart lightdm.service. About 10 or so seconds later, I have a graphical login and can login to my cinnamon desktop.Happy to provide any log or diagnostic output.
mkey commentedon Oct 23, 2025
@justindemuro if you follow my exchange with @leigh123linux you will likely find the needed steps to at least stop LMDE from dropping to TTY.
/usr/share/lightdm/lightdm.conf.d/50-minimum-vt.confand inputslick-greeteris installedlightdm-autologin-greeterandlightdm-gtk-greeterare not installedwiedaar commentedon Nov 17, 2025
i already have linux mint 22.2 and i wanted to have lmde7 on my other drive.
I have installed a lot of distro's to try and i could install them all without any problems.
But when i boot from usb to intall lmde i got this error, mount :
mounting efivars on /sys/firmware/efi/efivars failed : no such device [ 1 .807198] nouveau 0000:01:00 .0 uknown chipset (1b5000a1).
After a few seconds i ended up in the terminal with : mint@mint
After a few hours of searching and trying i managed to got in the setup, after that i got back in the terminal, installed the nvidia drivers but i ended up back in the prompt, this time onder my name. startx didnt do anything.
So, i whiped everything of the disk, and then i saw this temp solution gdm3.
I don't feel like starting doing this al over again.
I have the nvidia 5070, as my only graphic output
I would like to know if the distro would get a fix so that we can install lmde7 to try out.
Thank you for all the great work!
IEM-60 commentedon Dec 29, 2025
The same happened to me on a new LMDE 7 install.
My system is also configured for auto-login.
The desktop is actually starting but it's on VT7 and you have to manually switch ctrl+alt+7 or logging at TTY1 and type "startx".
None of the fixes suggested worked for me.
Doing that edit to the lightdm.conf file, helped but I experienced graphical glitches and my auto-start apps failed to start with that method...
Seems like the best solution is to install the nvidia-open drivers that are newer and more updated than the drivers from the Debian repo. This can be seen in a Youtube video from the channel A1RM4X. It's a 4hr long video testing LMDE 7. It happened live and he fixed it that way.
The way I could fix it is by removing the
"quiet splash"part from grub.So you have to edit
/etc/default/grubLook for this line:
GRUB_CMDLINE_LINUX_DEFAULT=""and ifquiet splashis there, delete it. I just left it blank.But be aware that there is an override file:
/etc/default/grub.d/50_lmde.confand this line:GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"was also present. So remove the quiet splash part.Then do
sudo update-gruband reboot.The system will start on the graphical desktop.
Maybe you can keep the quiet part and only remove the splash, if you don't want to see everything that's going on at boot, I'm not sure.
It's funny because even before attempting any fix, if you start LMDE 7 on recovery mode, it will start on the desktop, so I'm not really sure what's the issue and why removing the splash is fixing it, but it worked for me.
patso23 commentedon Jan 13, 2026
Can confirm this worked for me even on the proprietary drivers. I had already removed quiet splash from the main grub file, but removing it from 50_lmde.conf as @IEM-60 suggested got me booting directly to the greeter correctly