AppImage - Black application window upon opening

[rivalary]

When launching the AppImage for 0.1.1, the application window opens up but is completely black. Trying to close the window shows (not responding) in the titlebar and a prompt to Terminate de.velorendb.kaon or wait longer appears.
When launching from terminal, the following output is displayed:

qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
appinfo.vdf version:  41  (June 2024)

Running ALVR first (to be used with a Quest 2) doesn't seem to change things.
This is running on Bazzite on Wayland.
GPU: RX 6900 XT

[LorenDB]

I suspect this may relate to Bazzite being immutable. I will need to spin up a Bazzite install to test, so it may take a few days until I can fully test this.

[rivalary]

I launched it on my laptop that is also running Bazzite and it started fine, but I wouldn't run any of my VR stuff on the laptop. Could it be because I have multiple Steam libraries on different partitions?

[LorenDB]

It shouldn't be, because I specifically fixed that bug in 0.1.1.

[LorenDB]

I have tested on a Bazzite install with two Steam drives configured and was unable to replicate the problem. Do you mind uploading your ~/.steam/steam/steamapps/libraryfolders.vdf so I can double-check that your Steam folders seem sane?

[rivalary]

Sure, no prob

[LorenDB]

Your libraryfolders.vdf doesn't have anything that jumps out at me as bad. I've added some more debug logging to Kaon. Please download the AppImage from this build with the new logging and run it. It should generate a log file in ~/.cache/LorenDB/Kaon which should help pinpoint where the app is hanging. Then please upload that log here.

[rivalary]

It seems it won't create the log file in .cache for whatever reason.

I executed the AppImage in console and each line returns an error saying "device not open" with regards to the log location.
Here's the console output with that error being spammed having been trimmed out:

./Kaon-x86_64.AppImage 
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:57] [qt.qpa.plugin] warning: Could not find the Qt platform plugin "wayland" in ""
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:57] [default] info: This log only represents the most recent run of Kaon!
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [default] warning: qrc:/qt-project.org/imports/QtQuick/Controls/Fusion/ToolButton.qml: QML IconImage: Cannot open: qrc:/qt/qml/dev/lorendb/kaon/qml/icons/view-refresh.svg
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [default] warning: qrc:/qt-project.org/imports/QtQuick/Controls/Fusion/ToolButton.qml: QML IconImage: Cannot open: qrc:/qt/qml/dev/lorendb/kaon/qml/icons/settings-configure.svg
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [default] warning: qrc:/qt-project.org/imports/QtQuick/Controls/Fusion/ToolButton.qml: QML IconImage: Cannot open: qrc:/qt/qml/dev/lorendb/kaon/qml/icons/delete.svg
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [default] warning: qrc:/qt-project.org/imports/QtQuick/Controls/Fusion/ToolButton.qml: QML IconImage: Cannot open: qrc:/qt/qml/dev/lorendb/kaon/qml/icons/download.svg
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [default] warning: qrc:/qt-project.org/imports/QtQuick/Controls/Fusion/ToolButton.qml: QML IconImage: Cannot open: qrc:/qt/qml/dev/lorendb/kaon/qml/icons/draw-arrow-back.svg
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [steam] info: Found Steam: "/home/mnicholl/.steam/steam"
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [itch] warning: Itch not found
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open
[2025-08-22T10:16:58] [heroic] info: Heroic not found
QIODevice::write (QFile, "/home/mnicholl/.cache/LorenDB/Kaon/kaon.log"): device not open

I think the program is expecting the directory to already exist when writing to the log file.

I manually created the directory structure and ran the AppImage again. Here's the log:

kaon.log

[LorenDB]

I think the program is expecting the directory to already exist when writing to the log file.

Oops, that is indeed a problem. I've fixed that bug :)

It looks like Kaon is hanging while it parses appid 1158310, which is apparently Crusader Kings III. I think the best path forward would be either (a) try uninstalling CKIII and see if that fixes the problem, or (b) build Kaon from source and run it through a debugger, if you are comfortable with that. At this point, I don't see any obvious code paths that could hang Kaon, so we're pretty much at the point where I am stumped unless I know exactly which line of code Kaon hangs on.

You could also try deleting your Steam's ~/.steam/steam/appcache/appinfo.vdf. appinfo.vdf is mostly a cache of extended info about all apps in your library; it's possible (albeit unlikely) that yours is bugged, causing Kaon to hang while parsing it. If you do try this, be forewarned that one or two Steam launcher settings might change, so I'd recommend making a backup and then restoring it afterwards. You will also need to restart Steam for it to regenerate appinfo.vdf.

[rivalary]

After uninstalling CKIII, it looks like Kaon does open, though it takes a very long time. Deleting the .vdf file and having Steam recreate it did not fix the issue, so perhaps it's the size of my (installed?) library. I'd imagine I'm not the only one with a large library.

Also, the drop-down list where you select the UEVR version is empty and an error appears, "Downloading UEVR release information failed. Please check your network connection." On my laptop (which loads Kaon within a second), it populates. Perhaps Kaon is taking so long to load that it interrupts the drop-down list from populating?

So, yeah. I'm not sure if having a checkbox inside the settings panel for "disable Steam library refresh on startup" along with a manual refresh button would be a good idea.

Thanks for creating this, even if I haven't had a chance to try it yet :)

[LorenDB]

In the latest commit, I've added a way to disable autoscanning stores. Open ~/.config/LorenDB/Kaon.conf and add this at the top:

[General]
autoscan=false

Then if you run the binary from the most recent action, it should not scan your library on startup.

[rivalary]

Thank you, I added the autoscan=false line, then started v0.2.1. It loaded up, though nothing in my library. I was hoping that it would remember what I had when it loaded successfully.

I tried the refresh button, but it locked up for a solid 10 minutes before I killed it.

I removed the autoscan line then launched the AppImage again. It's been running for quite some time, so I think it's stuck not loading my library at all.

No worries if it simply won't work with a library as big as what I have. Thanks for the help.

[LorenDB]

I'm sorry that I can't figure out what's wrong, but I just can't see how it would be crashing. I'll leave this issue open in case somebody else experiences the same problem and does some debugging.

[rivalary]

Don't be sorry, thanks for all the help!

[boxxie79]

i have the same problem. hitting refresh gives an error claiming "failed to parse app manifest"

[LorenDB]

It looks like appmanifest_3527290.acf might be corrupt or empty. Do you mind uploading it here so I can get an idea why it might be breaking?