Kdenlive Crash on Fedora

I have made a little video from footage that I captured. Also I added some voice-over audio recording. For creating the video I use Kdenlive on Linux. This is my project:

In order to export this to Twitter, I need to export the project. So I open the export dialog and just select one of the default formats.

A few seconds later, the rendering has just aborted. Well, that does not really help much!

Also in the rendering dialog, there is just the hint that it has crashed. This does not help at all. I have repeated it a few times, but nothing changes, it always crashes with the same thing.

Looking for a stack trace

Looking into the system journal, I found this crash right around the time. It fits, because Kdenlive uses the MLT framework.

Jul 28 09:52:34 mu-x220 systemd-coredump[82646]:
  Process 82642 (mlt-melt) of user 1000 dumped core.

  Stack trace of thread 82642:
  #0  0x00007f5b859ad9e5 raise (libc.so.6 + 0x3c9e5)
  #1  0x00007f5b85996895 abort (libc.so.6 + 0x25895)
  #2  0x00007f5b7d8f1a7f _ZNK14QMessageLogger5fatalEPKcz (libQt5Core.so.5 + 0x91a7f)
  #3  0x00007f5b7de65e85 _ZN13QFontDatabaseC2Ev.cold (libQt5Gui.so.5 + 0xeae85)
  #4  0x00007f5b746ca5cb _ZL5fontsv (libpbf.so + 0x2e5cb)
  #5  0x00007f5b746caa85 _ZN4Font13fromJsonArrayERK10QJsonArray (libpbf.so + 0x2ea85)
  #6  0x00007f5b746ba879 _ZN5Style5Layer6LayoutC1ERK11QJsonObject (libpbf.so + 0x1e879)
  #7  0x00007f5b746beee7 _ZN5Style5LayerC1ERK11QJsonObject (libpbf.so + 0x22ee7)
  #8  0x00007f5b746c08a0 _ZN5Style4loadERK7QString (libpbf.so + 0x248a0)
  #9  0x00007f5b746b5a88 _ZN9PBFPluginC2Ev (libpbf.so + 0x19a88)
  #10 0x00007f5b746d5375 qt_plugin_instance (libpbf.so + 0x39375)
  #11 0x00007f5b7dab3564 _ZN15QLibraryPrivate14pluginInstanceEv (libQt5Core.so.5 + 0x253564)
  #12 0x00007f5b7daae16d _ZNK14QFactoryLoader8instanceEi (libQt5Core.so.5 + 0x24e16d)
  #13 0x00007f5b7def0fa6 _ZL23createReadHandlerHelperP9QIODeviceRK10QByteArraybb (libQt5Gui.so.5 + 0x175fa6)
  #14 0x00007f5b7def1d84 _ZN19QImageReaderPrivate11initHandlerEv (libQt5Gui.so.5 + 0x176d84)
  #15 0x00007f5b7def27e0 _ZNK12QImageReader7canReadEv (libQt5Gui.so.5 + 0x1777e0)
  #16 0x00007f5b7ebc17fa init_qimage (libmltqt.so + 0x167fa)
  #17 0x00007f5b7ebbcdf5 producer_qimage_init (libmltqt.so + 0x11df5)
  #18 0x00007f5b85cf6542 mlt_factory_producer (libmlt.so.6 + 0x29542)
  #19 0x00007f5b7ea5308e create_producer (libmltcore.so + 0xa08e)
  #20 0x00007f5b7ea536a9 producer_loader_init (libmltcore.so + 0xa6a9)
  #21 0x00007f5b85cf6542 mlt_factory_producer (libmlt.so.6 + 0x29542)
  #22 0x00007f5b85d17c90 on_end_element (libmltxml.so + 0x9c90)
  #23 0x00007f5b856a10cd xmlParseEndTag1.constprop.0 (libxml2.so.2 + 0x4a0cd)
  #24 0x00007f5b856a11c4 xmlParseElementEnd (libxml2.so.2 + 0x4a1c4)
  #25 0x00007f5b856a5721 xmlParseContent (libxml2.so.2 + 0x4e721)
  #26 0x00007f5b856a6dc0 xmlParseDocument (libxml2.so.2 + 0x4fdc0)
  #27 0x00007f5b85d18dce producer_xml_init (libmltxml.so + 0xadce)
  #28 0x00007f5b85cf6542 mlt_factory_producer (libmlt.so.6 + 0x29542)
  #29 0x00007f5b7ea532a1 create_producer (libmltcore.so + 0xa2a1)
  #30 0x00007f5b7ea536a9 producer_loader_init (libmltcore.so + 0xa6a9)
  #31 0x00007f5b85cf6542 mlt_factory_producer (libmlt.so.6 + 0x29542)
  #32 0x00007f5b7ea547fa producer_melt_init (libmltcore.so + 0xb7fa)
  #33 0x00007f5b85cf6542 mlt_factory_producer (libmlt.so.6 + 0x29542)
  #34 0x0000558ec88772b5 main (mlt-melt + 0x32b5)
  #35 0x00007f5b85998042 __libc_start_main (libc.so.6 + 0x27042)
  #36 0x0000558ec887838e _start (mlt-melt + 0x438e)

These can be reported via gnome-abrt to the Fedora project. So I have opened the program and indeed saw the crash there.

One can look at the details of that, but it does not tell me much.

Somehow the reporting fails, it seems that the service cannot be reached any more. This means that I cannot report this issue using the normal way.

Ask Fedora

I have described the issue on Ask Fedora where they told me that the reporting of stack traces is currently not possible due to a migration of the infrastructure. I should rather directly report the issue with the KDE project.

KDE bug report

Then I went to the KDE project and reported the bug there. I was asked to use the app images provided by KDE to see whether this is a fundamental issue with KDE or rather only with the Fedora packaging.

Using the appropriate app image (20.04b) I have been able to render the video fine. The problem was that the video showed up just white in both the preview and the rendered version. In my case it wasn't filenames with spaces, though it was a good hint. I had moved the video files outside of Kdenlive and the program found them again. I have just deleted them from the project and added them again, then it showed up.

As I was then able to render the video just fine, the issue must be somewhere in the Fedora packaging.

Fedora bug report

As this is a Fedora issue, I have reported it as a bug there. Now this will hopefully get worked on. In either case Fedora uses can just use the KDE AppImage until this is resolved.