Sigil crashes in UbutuStudio 26.04 - Page 2

KevinH · 04-30-2026, 04:56 PM

One last thing to try, please modify your env-vars.txt file to enable more debug output as follows:

Code:

QTWEBENGINE_CHROMIUM_FLAGS="--enable-logging"
QT_LOGGING_RULES="qt.webenginecontext=true;qt.webengine.compositor=true"

Then try starting up Sigil from a terminal command line prompt.

If that doesn't show any debug info, then I am out of ideas.

Please let me know what you find.

As I do not have the same shared libraries as you do, your coredump will not be any use to me even though I have Linux.

DiapDealer · 04-30-2026, 06:30 PM

I'm a little stuck in the way of help on this right now. My Arch system is acting up after an update right now. I can launch Cinnamon Wayland and Gnome (also Wayland) sessions (Sigil AppImage still works), but I cannot launch my preferred Cinnamon Xorg session.

It can't be anything too drastic since my Cinnamon Desktop is still there using a Wayland session, but I'm absolutely not ready to abandon Xorg just yet, so I have to figure it out.

KevinH · 04-30-2026, 06:34 PM

Manjaro kde moved me to wayland only and removed the plasma-x11 option with no warning during my last update.

Stinks, but I will re-add it. They should not have done that without asking.

DiapDealer · 04-30-2026, 07:45 PM

Not only has the update to GDM 50 moved to Wayland only, it has somehow discovered a way to not be able to even launch an X session. Moving to LightDM and the LightDM greeter got me back up and running with my beloved Cinnamon x11 desktop/session.

The moral of the story appears to be: Do not use the Gnome Display Manager to launch anything other than a Gnome session.

I get that x11 has been completely removed from Gnome 50 (and that their display manager cannot launch a Gnome x11 session), but how can the Gnome Display Manager not launch a completely different DE that DOES support x11?? It's stupid. But whatever... I'm over it.

philja · 05-01-2026, 07:57 AM

Quote:

Originally Posted by KevinH

One last thing to try, please modify your env-vars.txt file to enable more debug output as follows:

Code:

QTWEBENGINE_CHROMIUM_FLAGS="--enable-logging"
QT_LOGGING_RULES="qt.webenginecontext=true;qt.webengine.compositor=true"

Then try starting up Sigil from a terminal command line prompt.

If that doesn't show any debug info, then I am out of ideas.

Please let me know what you find.

As I do not have the same shared libraries as you do, your coredump will not be any use to me even though I have Linux.

OK - I edited env-vars.txt to have just your two lines above and launched Sigil from the
command line. It crashed as expected.

Here is what I saw in the terminal:

Spoiler:

and this is what was in the crash report :

Spoiler:

Hope you can see something useful there.

philja · 05-01-2026, 08:00 AM

Quote:

Originally Posted by DiapDealer

Not only has the update to GDM 50 moved to Wayland only, it has somehow discovered a way to not be able to even launch an X session. Moving to LightDM and the LightDM greeter got me back up and running with my beloved Cinnamon x11 desktop/session.

The moral of the story appears to be: Do not use the Gnome Display Manager to launch anything other than a Gnome session.

I get that x11 has been completely removed from Gnome 50 (and that their display manager cannot launch a Gnome x11 session), but how can the Gnome Display Manager not launch a completely different DE that DOES support x11?? It's stupid. But whatever... I'm over it.

What are the supposed advantages of Wayland? X11 worked just fine and Wayland seems to have caused problems for several years now.

Now, with the env-vars.txt entries which enable me to start Sigil without a crash, Sigil takes much longer to start than I've ever seen before. A first launch takes up to 10 seconds with subsequent launches taking around 4 secs.

KevinH · 05-01-2026, 09:22 AM

The error messages in your last post show that Qt is trying to use Vulkan (just like the other related error messages). Are you absolutely sure your graphics card driver supports Vulkan?

The second thing I saw is about an app sandbox being used, but using a sandbox with any app like Sigil is simply not a good idea. Not sure is adding the option to turn off the sandbox would help or not.

I found 3 vulkan related packages for your system:

vulkan-tools
vulkan-utils
mesa-vulkan-drivers

That last one is key.

Please make sure all 3 are installed on your system and if not present install-them.

Next try running this command to see what graphics card you have and which driver it uses:

lspci -k | grep -i VGA

Please let us know what you find.

KevinH · 05-01-2026, 09:31 AM

There may be a second issue at play ...
see this link ...

https://chromium.googlesource.com/ch...estrictions.md

So your new ubuntu has added a new AppArmor security feature that may be killing things your unpriviledged user id is trying to run.

That post tells you how on Ubuntu to turn it off.

I personally think Ubuntu has finally gone over the deep end, turning on a feature like AppArmor by default for a single user Linux box. That is completely for the birds.

I am sure it slows down start-up of any app it deems suspicious.

Maybe adding "--no-sandbox" to the QtWebEngineFlags env var will help?

DiapDealer · 05-01-2026, 09:32 AM

You can safely ignore the following (unless the fallback to vulkan is causing the crash--it doesn't on my system):

Code:

Warning: GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.

It's very common and goes away with QT_QUICK_BACKEND=software.

This next one about sandboxing is a bit concerning. Looks like AppArmor has set itself up as some sort of Chrome process gatekeeper on Ubuntu

I'm not sure what to make of the next two warnings

The org.freedesktop.portal.Error.Failed is slightly concerning. I've never seen this one. I get warnings about duplicate org.freedesktop.portal registrations all the time, but they seem pretty innocuous. Not sure what a straight-up failure to register the app with dbus might imply.

DiapDealer · 05-01-2026, 09:47 AM

For the record. I don't think AppArmor is trying to sandbox the webengine process itself. I think it's webengine's default. AppArmor just doesn't seem to let unprivileged user processes initiate one. Also QtWebEngine seems to acknowledge that this is a problem. From the Qt6.11 documentation:

Quote:

Qt WebEngine provides out-of-the-box sandboxing support for Chromium render processes.

On Linux, note the following restrictions:

The kernel has to support the anonymous namespaces feature (kernel version 3.8 or later). However, on Debian, Ubuntu, and other Debian-derived distributions, this feature is off by default. It can be turned on by setting /proc/sys/kernel/unprivileged_userns_clone to 1.
The kernel has to support the seccomp-bpf feature (kernel version 3.5 or later).
Setuid sandboxes are not supported and are thus disabled.
To explicitly disable sandboxing, use one of the following options:

Set the QTWEBENGINE_DISABLE_SANDBOX environment variable to 1.
Pass the --no-sandbox command line argument to the user application executable.
Set QTWEBENGINE_CHROMIUM_FLAGS to --no-sandbox

This all sounds like a bit of a deathknell for QtWebEngine applications on Ubuntu. It's like they think the Chrome browser is the only Chrome render process that might exist on a system

KevinH · 05-01-2026, 09:48 AM

Check out this post about how AppImage users may have to create their own AppArmor profiles.

https://askubuntu.com/questions/1528...528720#1528720

It seems their snap packages already work with their new AppArmor but of course AppImages do not!

Personally, I would run away from Ubuntu so fast it would not be funny!

KevinH · 05-01-2026, 09:52 AM

Quote:

Originally Posted by DiapDealer

You can safely ignore the following (unless the fallback to vulkan is causing the crash--it doesn't on my system):

Code:

Warning: GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.

But he may not even have the mesa-vulkan-drivers installed yet so his system may actually be trying to use vulkan and not egl with opengl.

I would still install the drivers just to rule that out.

DiapDealer · 05-01-2026, 10:01 AM

Quote:

Originally Posted by KevinH

But he may not even have the mesa-vulkan-drivers installed yet so his system may actually be trying to use vulkan and not egl with opengl.

I would still install the drivers just to rule that out.

Absolutely.

DiapDealer · 05-01-2026, 10:04 AM

Quote:

Originally Posted by KevinH

Check out this post about how AppImage users may have to create their own AppArmor profiles.

https://askubuntu.com/questions/1528...528720#1528720

It seems their snap packages already work with their new AppArmor but of course AppImages do not!

Personalky, I would run away from Ubuntu so fast it would not be funny!

What a huge pain in the ass to expect users to create AppArmor exemption profiles.

DiapDealer · 05-01-2026, 10:15 AM

The only thing that has me confused is how our AppImage is able to work around this issue merely by setting QT_QUICK_BACKEND to software and turning off hardware acceleration in QtWebEngine?

If the need for unprivileged usernamespaces is AppImage-centric, I wouldn't think any of Qt's env vars would have an effect on that.

That debug output @philja posted indicates the sandbox messages for Sigil are INFO only. The debug output on the page you linked are FATAL. Perhaps AppArmor is not the source of the crash? I think we might just be back to video driver stuff.

04-30-2026, 04:56 PM	#16
KevinH Sigil Developer Posts: 9,675 Karma: 6774048 Join Date: Nov 2009 Device: many	One last thing to try, please modify your env-vars.txt file to enable more debug output as follows: Code: QTWEBENGINE_CHROMIUM_FLAGS="--enable-logging" QT_LOGGING_RULES="qt.webenginecontext=true;qt.webengine.compositor=true" Then try starting up Sigil from a terminal command line prompt. If that doesn't show any debug info, then I am out of ideas. Please let me know what you find. As I do not have the same shared libraries as you do, your coredump will not be any use to me even though I have Linux. Last edited by KevinH; 04-30-2026 at 05:20 PM.

05-01-2026, 09:22 AM	#22
KevinH Sigil Developer Posts: 9,675 Karma: 6774048 Join Date: Nov 2009 Device: many	The error messages in your last post show that Qt is trying to use Vulkan (just like the other related error messages). Are you absolutely sure your graphics card driver supports Vulkan? The second thing I saw is about an app sandbox being used, but using a sandbox with any app like Sigil is simply not a good idea. Not sure is adding the option to turn off the sandbox would help or not. I found 3 vulkan related packages for your system: vulkan-tools vulkan-utils mesa-vulkan-drivers That last one is key. Please make sure all 3 are installed on your system and if not present install-them. Next try running this command to see what graphics card you have and which driver it uses: lspci -k \| grep -i VGA Please let us know what you find. Last edited by KevinH; 05-01-2026 at 09:25 AM.

05-01-2026, 09:31 AM	#23
KevinH Sigil Developer Posts: 9,675 Karma: 6774048 Join Date: Nov 2009 Device: many	There may be a second issue at play ... see this link ... https://chromium.googlesource.com/ch...estrictions.md So your new ubuntu has added a new AppArmor security feature that may be killing things your unpriviledged user id is trying to run. That post tells you how on Ubuntu to turn it off. I personally think Ubuntu has finally gone over the deep end, turning on a feature like AppArmor by default for a single user Linux box. That is completely for the birds. I am sure it slows down start-up of any app it deems suspicious. Maybe adding "--no-sandbox" to the QtWebEngineFlags env var will help? Last edited by KevinH; 05-01-2026 at 09:36 AM.

05-01-2026, 09:32 AM	#24
DiapDealer Grand Sorcerer Posts: 29,459 Karma: 212177022 Join Date: Jan 2010 Device: Nexus 7, Kindle Fire HD	You can safely ignore the following (unless the fallback to vulkan is causing the crash--it doesn't on my system): Code: Warning: GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium. It's very common and goes away with QT_QUICK_BACKEND=software. This next one about sandboxing is a bit concerning. Looks like AppArmor has set itself up as some sort of Chrome process gatekeeper on Ubuntu I'm not sure what to make of the next two warnings The org.freedesktop.portal.Error.Failed is slightly concerning. I've never seen this one. I get warnings about duplicate org.freedesktop.portal registrations all the time, but they seem pretty innocuous. Not sure what a straight-up failure to register the app with dbus might imply.

05-01-2026, 09:48 AM	#26
KevinH Sigil Developer Posts: 9,675 Karma: 6774048 Join Date: Nov 2009 Device: many	Check out this post about how AppImage users may have to create their own AppArmor profiles. https://askubuntu.com/questions/1528...528720#1528720 It seems their snap packages already work with their new AppArmor but of course AppImages do not! Personally, I would run away from Ubuntu so fast it would not be funny! Last edited by KevinH; 05-01-2026 at 10:44 AM.

04-30-2026, 06:30 PM	#17
DiapDealer Grand Sorcerer Posts: 29,459 Karma: 212177022 Join Date: Jan 2010 Device: Nexus 7, Kindle Fire HD	I'm a little stuck in the way of help on this right now. My Arch system is acting up after an update right now. I can launch Cinnamon Wayland and Gnome (also Wayland) sessions (Sigil AppImage still works), but I cannot launch my preferred Cinnamon Xorg session. It can't be anything too drastic since my Cinnamon Desktop is still there using a Wayland session, but I'm absolutely not ready to abandon Xorg just yet, so I have to figure it out.

04-30-2026, 06:34 PM	#18
KevinH Sigil Developer Posts: 9,675 Karma: 6774048 Join Date: Nov 2009 Device: many	Manjaro kde moved me to wayland only and removed the plasma-x11 option with no warning during my last update. Stinks, but I will re-add it. They should not have done that without asking.

04-30-2026, 07:45 PM	#19
DiapDealer Grand Sorcerer Posts: 29,459 Karma: 212177022 Join Date: Jan 2010 Device: Nexus 7, Kindle Fire HD	Not only has the update to GDM 50 moved to Wayland only, it has somehow discovered a way to not be able to even launch an X session. Moving to LightDM and the LightDM greeter got me back up and running with my beloved Cinnamon x11 desktop/session. The moral of the story appears to be: Do not use the Gnome Display Manager to launch anything other than a Gnome session. I get that x11 has been completely removed from Gnome 50 (and that their display manager cannot launch a Gnome x11 session), but how can the Gnome Display Manager not launch a completely different DE that DOES support x11?? It's stupid. But whatever... I'm over it.

05-01-2026, 10:15 AM	#30
DiapDealer Grand Sorcerer Posts: 29,459 Karma: 212177022 Join Date: Jan 2010 Device: Nexus 7, Kindle Fire HD	The only thing that has me confused is how our AppImage is able to work around this issue merely by setting QT_QUICK_BACKEND to software and turning off hardware acceleration in QtWebEngine? If the need for unprivileged usernamespaces is AppImage-centric, I wouldn't think any of Qt's env vars would have an effect on that. That debug output @philja posted indicates the sandbox messages for Sigil are INFO only. The debug output on the page you linked are FATAL. Perhaps AppArmor is not the source of the crash? I think we might just be back to video driver stuff. Last edited by DiapDealer; 05-01-2026 at 10:28 AM.

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