Login manager loops on Wayland KDE, and can't start graphic session on TTY

General system Kernel, boot, graphics & hardware
1

In the middle of the last update (today, after one week without update) I got a strange message, similar to “loging screen is broken” go to other TTY to unlock, and return to TTY 2. I did this, and could continue the update. Then when rebooting, Wayland won’t launch.
I am stuck in the KDE plasma manager. can write my password but I return to the login screen. I can enter a TTY but I can’t either launch Wayland from there.
One message I get is : Error: fuse init failed : can’t mount path /run/user/1000/doc
followed by a lot of
Glib-GIO-CRITICAL **: Error while … message: the connection is closed
and at the end : org.kde.plasma.waitforname: Waitforname:cService was not registered within timeout

I have try to log on X, but the only thing I managed to get is a console on a black desktop
Any idea how to regain my Plasma session ?
(I also have btrfs assistant running with snapper snapshots, but I don’t know how to restore a snapshot without a graphical environment

Which info would you need to debug this issue ?

2

More relevant info ? (Maybe)
Trying to chroot, I get mount: /mnt/home: wrong fs type, bad option, bad superblock on /dev/nvme0n1p2, missing codepage or helper program or other error.

First type I get this message, chroot worked in the past (I am on BTRFS system, without LUKS)

3

@pierrep56

Make sure to follow the mounting according to EOS’ subvolume scheme.

Please look here (scroll down to " BTRFS filesystem installs")

https://discovery.endeavouros.com/system-rescue/arch-chroot/2022/12/

4

I did. It’s the same sheme and process I have used many times, and it was working. Just now it does not

5

Try mounting the root of your btrfs partition (not any specific subvolumes) and run a scrub and see if it reports any errors.

If /dev/nvme0n1p2 is the btrfs partition:

sudo mount -t btrfs /dev/nvme0n1p2 /mnt

sudo btrfs scrub start /mnt

6

It returns no error (but was VERY rapid, so I wonder if it even worked)

7

Not sure what to make of it :thinking:

With your partition still mounted on /mnt, could you post:

sudo btrfs subvolume list /mnt

sudo btrfs filesystem usage /mnt

?

8

This is the subvolume lists (with a bunch of snapshots… If you know how to revert to an older snapshot from the CLI, this could be a solution)

ID 256 gen 108340 top level 5 path @
ID 257 gen 108336 top level 5 path @home
ID 258 gen 108335 top level 5 path @cache
ID 259 gen 108336 top level 5 path @log
ID 260 gen 6912 top level 5 path @swap
ID 261 gen 6676 top level 256 path @/var/lib/portables
ID 262 gen 6676 top level 256 path @/var/lib/machines
ID 266 gen 108335 top level 256 path @/.snapshots
ID 2601 gen 107770 top level 266 path @/.snapshots/2335/snapshot
ID 2733 gen 107770 top level 266 path @/.snapshots/2467/snapshot
ID 2774 gen 107770 top level 266 path @/.snapshots/2508/snapshot
ID 2810 gen 107770 top level 266 path @/.snapshots/2544/snapshot
ID 2847 gen 107770 top level 266 path @/.snapshots/2581/snapshot
ID 2848 gen 107770 top level 266 path @/.snapshots/2582/snapshot

9

And this is the result of the filesystem usage (Doesn’t seems to be the issue)

udo btrfs filesystem usage /mnt
Overall:
Device size: 1.82TiB
Device allocated: 392.12GiB
Device unallocated: 1.43TiB
Device missing: 0.00B
Device slack: 3.00KiB
Used: 347.58GiB
Free (estimated): 1.47TiB (min: 776.13GiB)
Free (statfs, df): 1.47TiB
Data ratio: 1.00
Metadata ratio: 2.00
Global reserve: 512.00MiB (used: 0.00B)
Multiple profiles: no

Data,single: Size:386.00GiB, Used:344.31GiB (89.20%)
/dev/nvme0n1p2 386.00GiB

Metadata,DUP: Size:3.00GiB, Used:1.63GiB (54.50%)
/dev/nvme0n1p2 6.00GiB

System,DUP: Size:64.00MiB, Used:64.00KiB (0.10%)
/dev/nvme0n1p2 128.00MiB

10

I could help you to restore one of these snapshots but with a few “caveats”:

  1. I am not a KDE Plasma user so I haven’t really looked into the error messages you have posted to know if there are no other solutions to your issue than restoring your @ or to know that the issue resides in @ at all.

  2. I know that there is “snapper rollback” but I have never used it myself so I am going about this “manually”.

So, if you feel “adventurous”, here it is:

(assuming that your btrfs partition is mounted at /mnt in the live session and @/.snapshots/2582/snapshot is the most recent snapshot of @)


sudo mv /mnt/@ /mnt/@-broken

sudo btrfs subvolume snapshot  /mnt/@-broken/.snapshots/2582/snapshot  /mnt/@

Before rebooting, I’d verify:

sudo btrfs subvolume list /mnt

and ensure there is a fresh @ subvolume and the old one is now @-broken.

Also, since you had issues mounting your @home before, I honestly cannot guaranty that this will resolve your issue. There you have it! Good luck!

11

Thanks, I got a new message in th eTTY, which I believe is closer to the issue:

qt.qpa.xcb: could not connect to display
qt.qpa.plugin: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is needed to load the Qt xcb platform plugin
qt.qpa.plugin: Could not load the Qt platform plugin “xcb” in " " even though it was found.
This application failed to start because no Qt platform plugin could be initialized.

I need to investigate if this is related