Where to begin troubleshooting not working on Ubuntu 22.04

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1

I’ve been unable to get a working Kdenlive installation on Ubuntu 22.04.

Aside from recommendations to try x, do z and “see if that fixes it” I’ve not found any in depth suggestion for troubleshooting. And there’s the question of what to troubleshoot, the application or it’s container.

Video was not captured by 12 different versions using four different package types. A couple failed to capture audio too. OBS Studio captures audio and video so I know the hardware and software is working.

And I’ve got a Q4OS laptop with a 22.12.3 .deb install working just fine so I know Kdenlive is what I’d like on my primary laptop.

On Ubuntu 22.04 the following were tried without success:
.deb - 21.12.3 and 23.08.5

Snap - 24.08.3 and 24.12.1

Appimage - 20.08.1, 21.08.3, 24.02.2, 22.04.3, 24.05.2, 24.12.0 and 25.03.70

FlatPak - 24.12.0

Any suggestion which installation type to focus on, and then where to find more detailed troubleshooting instructions?

Thank you.

2

You need to provide actual errors here - nobody can guess.

Even though you said ‘Ubuntu’ we can’t guess what you did to your system, or why something won’t install or run.

3

Is there some page where to learn how to troubleshoot things, which we can link? This would be the most useful resource for OP.

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4

As @ben2talk mentioned, it’s impossible to troubleshoot without seeing the actual error messages you’re facing. The best way to do this is to run the software in a terminal window and see that text gets printed.

However my suspicion is that Ubuntu 22.04 is simply too old to work with some newer software versions. I doubt any KDE developers are testing their apps on 3 year-old Ubuntu versions. If it works at all, it’s probably a coincidence.

If you can, at least updating to Ubuntu 24.04 will probably help — not only with this, but with other miscellaneous gremlins in the system too.

And going all the way to Ubuntu 24.10 would put you much closer to what KDE developers are themselves using and testing on.

5

Video capture doesn’t really work in Kdenlive. This is a feature that needs fixing but took back rows over the last years. I am pretty sure it has nothing to do with your OS and distro (I am using Pop!_OS 22.04 LTS which is based on Ubuntu, and Kdenlive works just fine except for video capture).

Audio capture is a different topic, and I can confirm that it works for me. An external microphone, if recognized by the OS, is all that’s needed.

6

Thank you for that information.

The fact that video (and audio) capture works in some installations, the Q4OS laptop I mentioned, and late last night I found it works on Windows 11 also, gave me hope.

An aside, the video capture in all those configurations where it captures anything either captures a black screen with a stationary mouse or a black screen with the mouse moving around on it.

That gave me an idea, can I capture the screen without the mouse (yes, check don’t capture the mouse) and capture the mouse only as a 2nd layer?

That would permit me to mask the screen where needed in editing and not have the mouse wink in and out by putting the mouse layer over the masking.

Any suggestions what to search for to solve that puzzle? None of my searches are getting me anywhere.

7

The error messages haven’t led to searches with useful troubleshooting info (for me), are different for different packages and also appear when launching the .deb installation on my Q4OS laptop which does work.

Suggesting Ubuntu 22.04 is too old is kinda anathema to the snap, AppImage, and FlatPak mantra “install it and it just works on any distribution with the daemon correctly set up”, that’s snap and FlatPak. And AppImage is “just mark it executable and it works”. And Ubuntu 22.04 is supported until 27.04, about 2 1/4 years more so I would expect it would work packaged in at least one of the .deb, snap, AppImage, or FlatPak.

but…
** .deb errors
running on Ubuntu 22.04 as follows
$ export QT_QPA_PLATFORM=wayland
$ kdenlive --mlt-log verbose kdenlive
The only warning in the output is the next line. The word “error” is not anywhere in the terminal output.
Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.

Plus 59 lines of “plugin not available: <some_plugin>”

…and the same is seen on Q4OS 5.7.1-n1 but on Q4OS both video and audio are captured.

** snap errors
Failed to load module “canberra-gtk-module”

** AppImage errors
$ export QT_QPA_PLATFORM=wayland
$ ./kdenlive-21.08.3a-x86_64.appimage
Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
QSocketNotifier: Can only be used with threads started with QThread
Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
qt.qpa.plugin: Could not find the Qt platform plugin “wayland” in “”
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: xcb.

** FlatPak errors: flatpak -vv run org.kde.kdenlive
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.

And you see “xcb” in both AppImage and FlatPak but the modules are installed and latest versions.

My initial question remains, Any suggestion which installation type to focus on, and then where to find more detailed troubleshooting instructions?

8

For starters, I’d recommend not doing this.

Next up, I’d experiment with installing plasma-integration and seeing if that helps.

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9

And that cheque is totally in the mail (:

A promise to best-effort fix critical security bugs in 2022 software is not the same thing as having 2026’s hoverboards work with it…

Wayland and screen capture is a long trail of tears. Google is full stories about the bodies lining that road.

Did you try the kdenlive documentation on exactly this?

10

I’m not so cynical. It’s easy to find “doesn’t work” posts. What I’m looking for are “solved” posts. Or at least those that provide insight to the troubleshooting done.

Plus, I expect the folks at AppImage are actually tyring to achieve what is promised. Mark it executable and it runs. Certainly does work for some apps across platforms.

True, it is not. However for Ubuntu’s snap platform Canonical’s mission is to make it work on supported platforms, e.g. Ubuntu 22.04. I will always check to see if that is acheived when it affects me. And I’ll look for solutions if something isn’t working.

I’ve read many of those posts and yes most don’t end well. However there are some that do and developers are incorporating Wayland into their applications. It’s not all gloom and doom.

And that environment variable was not initially set. It was set only because that is suggested in the terminal output when running the program.

When it’s included in the instructions I give it a try.

Oh yeah, I’ve been there. NOT helpful.

Per my initial post, looking for troubleshooting, e.g. check for this, check for that, based on what’s found try this for that error or that for this other error.

Not at all what I’ve found. It’s all “try changing x and see if that fixes it”. And if it doesn’t work then “try changing y and see if that fixes it.”

That’s not troubleshooting, that’s just blindly flipping bits.

11

I tried export QT_QPA_PLATFORM=wayland because that is what is suggested in the terminal when the program is started from the terminal.

My understanding is that of the format’s I’ve tried only the .deb might be affected by the presence of a plasma-integration package. The others, AppImage, snap, FlatPak, should all take care of any such dependency in the app package.

I did check and plasma-integration was not installed.

I installed it and tried all the packages again. All still failed to capture video.

12

When there’s lots of the first, and none of the second, saying but, but, but, I was promised! does you about as much good as handwaving away the first group as “cynics”.

Well you still haven’t at all reported on what the tests suggested there show on your system, so …

… evidently you don’t.