Bug 480964

If something crashed, we need a backtrace of it so we can figure out what's going on. Can you please attach a backtrace of the crash using the coredumpctl command-line program, as detailed in https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports#Retrieving_a_backtrace_using_coredumpctl?

Thanks!

(In reply to Nate Graham from comment #1)
> If something crashed, we need a backtrace of it so we can figure out what's
> going on. Can you please attach a backtrace of the crash using the
> coredumpctl command-line program, as detailed in
> https://community.kde.org/Guidelines_and_HOWTOs/Debugging/
> How_to_create_useful_crash_reports#Retrieving_a_backtrace_using_coredumpctl?
> 
> Thanks!

Thank you the feedback, Nate! Unfortunately I got nothing. I crashed an application (in this case Signal), then ran coredumpctl --reverse in the command line... but it just says "No coredumps found".

I tried running Signal using the command line, and crashing it on purpose. But again, same result. Is there anything else I can try?

If coredumpctl isn't working, you can manually run the app in a debugger with `gdb $(which signal)`. Then type `run`. Then make it crash. Then type `bt`. Then when prompted to download debug symbols type `y`. Then when prompted to continue paging, hit `c`. Copy and paste the backtrace into here.

This assumes `signal` is the name of the binary for the app; if it's not, you may need to adjust that appropriately

(In reply to Nate Graham from comment #3)
> If coredumpctl isn't working, you can manually run the app in a debugger
> with `gdb $(which signal)`. Then type `run`. Then make it crash. Then type
> `bt`. Then when prompted to download debug symbols type `y`. Then when
> prompted to continue paging, hit `c`. Copy and paste the backtrace into here.
> 
> This assumes `signal` is the name of the binary for the app; if it's not,
> you may need to adjust that appropriately

Thank you again for your help! But I can't get the debugger to run the app, for some reason. It doesn't open when I press run (but I confirmed it opens if I just type "signal-desktop" without the debugger being running, so the name is correct). Here is the code I get from the command line:

```
mrbig@solenodon:~$ gdb signal-desktop
GNU gdb (Ubuntu 12.1-0ubuntu1~22.04) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from signal-desktop...
(No debugging symbols found in signal-desktop)
(gdb) run
Starting program: /snap/bin/signal-desktop 

This GDB supports auto-downloading debuginfo from the following URLs:
https://debuginfod.neon.kde.org/:
Enable debuginfod for this session? (y or [n]) y
Debuginfod has been enabled.
To make this setting permanent, add 'set debuginfod enabled on' to .gdbinit.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffd10ee640 (LWP 6329)]
[New Thread 0x7fffc88ed640 (LWP 6330)]
[New Thread 0x7fffd08ed640 (LWP 6331)]
[New Thread 0x7fffcbfff640 (LWP 6332)]
[New Thread 0x7fffcb7fe640 (LWP 6333)]
[Thread 0x7fffc88ed640 (LWP 6330) exited]
[Thread 0x7fffcb7fe640 (LWP 6333) exited]
[Thread 0x7fffcbfff640 (LWP 6332) exited]
[Thread 0x7fffd08ed640 (LWP 6331) exited]
[Thread 0x7fffd10ee640 (LWP 6329) exited]
process 6325 is executing new program: /snap/snapd/20671/usr/bin/snap
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffd10de640 (LWP 6334)]
[New Thread 0x7fffd08dd640 (LWP 6335)]
[New Thread 0x7fffcbfff640 (LWP 6336)]
[New Thread 0x7fffcb7fe640 (LWP 6337)]
[New Thread 0x7fffcaffd640 (LWP 6338)]
[Detaching after vfork from child process 6339]
[New Thread 0x7fffca7bc640 (LWP 6345)]
[New Thread 0x7fffc9fbb640 (LWP 6346)]
[New Thread 0x7fffc97ba640 (LWP 6347)]
[New Thread 0x7fffc8f79640 (LWP 6348)]
[New Thread 0x7fffa7fff640 (LWP 6349)]
[Thread 0x7fffa7fff640 (LWP 6349) exited]
[Thread 0x7fffc97ba640 (LWP 6347) exited]
[Thread 0x7fffc9fbb640 (LWP 6346) exited]
[Thread 0x7fffca7bc640 (LWP 6345) exited]
[Thread 0x7fffcaffd640 (LWP 6338) exited]
[Thread 0x7fffcb7fe640 (LWP 6337) exited]
[Thread 0x7fffcbfff640 (LWP 6336) exited]
[Thread 0x7fffd08dd640 (LWP 6335) exited]
[Thread 0x7fffd10de640 (LWP 6334) exited]
process 6325 is executing new program: /snap/snapd/20671/usr/lib/snapd/snap-confine
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
need to run as root or suid
[Inferior 1 (process 6325) exited with code 01]
(gdb)
```

You'd need to debug Xwayland, not the app itself. To do that you'd need to use an ssh session from a different PC though, as halting Xwayland for debugging can sometimes also freeze kwin, so you could never unfreeze it from the same PC.

Before we go there though, if coredumpctl doesn't work, it's likely the issue is caused by an assert, or by a Wayland error.
Those will be visible in the log, so you should check it for a hint about what happened. If you execute
journalctl --user --boot 0 --follow
(and leave it running) and then trigger the Xwayland crash, you should see some message about the crash in the terminal.

Sorry for not responding earlier, I got caught up with work.

I updated to Plasma 6, and this issue got resolved. Thank you for your help and patience!

I have similar behaviour on wayland-1.22 with plasma6

E.g. libreoffice crashes when I scroll with the mouse (not with the touchpad though), in the logs I see the following:

XWAYLAND: interface "wl_pointer" has no event 9

I had to update following packages from Neon testing to make the error stop:

libwayland-bin libwayland-client0 libwayland-cursor0 libwayland-egl1

They should be included in neon user repository IMO.

I assume this is fixed in the latest version, reading the last comments here.