Thanks for your report! Usually the depreciation message shouldn't lead to a crash. I guess the problem occurs only with a certain project? Do use any effects, compositions etc. in the project? Can you maybe attach a *.kdenlive file that leads to the crash?

Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!

Created attachment 137817 [details]
kdenlive project

Created attachment 137818 [details]
video clip to use

I can confirm this bug, in my case it occurs now on all renders (before I was able to make it work by rendering via a selection starting at the beginning of the project and ending at the end of the project... but now the trick is not enough). It occurs even with a single clip (.mp4 or .MOV), no effect, and outputting in .mp4 or .webm (generic, custom defaults, I did not tried all the others). You can find a minimal bugging project attached, with a screenshot.

The message I get when rendering is:

"Le rendu de /tmp/kdenlive_bug/rendu.mp4 a été interrompu par une erreur fatale

[mp4 @ 0x7f23ac000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead. [mp4 @ 0x7f23ac000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead."

I also have a log file that appears:

Started render process: /nix/store/vm0pkg81p2cpxwpgkm14i2dhbpsk59i4-mlt-6.24.0/bin/melt -progress /tmp/kdenlive-DHNspc.mlt
[mp4 @ 0x7f23ac000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead. [mp4 @ 0x7f23ac000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.Rendering of /tmp/kdenlive_bug/rendu.mp4 aborted, resulting video will probably be corrupted.

but the .mlt file does not exist:
$ cat /tmp/kdenlive-DHNspc.mlt
cat: /tmp/kdenlive-DHNspc.mlt: No such file or directory

I'm using:
- Kdenlive 20.12.2
- MLT 6.24.0
- Installed in NixOs, via the nix package manager, using the channel nixos-unstable (updated today), commit d235056d6d6, install via the command `nix-env -iA nixos.kdenlive`.

Created attachment 137821 [details]
screenshot

PS: I tried to export to other formats (audio only .mp3, png/gif sequences... They all fail. However, when I want to export to MPEG, I get a different kind of error, no idea if it can be related or if it's another bug:

Le rendu de /tmp/kdenlive_bug/rendu.mpg a été interrompu par une erreur fatale

[mpeg2video @ 0x7f0258001c40] [Eval @ 0x7f026755cf30] Invalid chars 'mp=1subcmp=1trellis=1bf=2' at the end of expression '3 cmp=1 subcmp=1 trellis=1 bf=2' [mpeg2video @ 0x7f0258001c40] Unable to parse option value "3 cmp=1 subcmp=1 trellis=1 bf=2"
[mpeg @ 0x7f0258000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead. [mpeg @ 0x7f0258000f40] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead. [mpeg @ 0x7f0258000f40] VBV buffer size not set, using default size of 230KB If you want the mpeg file to be compliant to some specification Like DVD, VCD or others, make sure you set the correct buffer size
[mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=2002 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=2002 size=31714
[mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=4043 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=6084 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=8125 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=10166 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=12207 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=14248 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=16289 size=31714
[mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=18330 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=20371 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=22412 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=24453 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=26494 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=28535 size=31714 [mpeg @ 0x7f0258000f40] buffer underflow st=0 bufi=30576 size=31714

Hum, actually I just realized that even if it says "project crashed", in my case the file is not corrupted (I was sure that on previous verions when the project crashed the file was actually corrupted... and can actually be played... Very strange.

Thanks for the info. Just this message does not tell that there is anything wrong or crashing:

Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.

However the file in the /tmp dir does only exist as long as the rendering is running. After it has been finished (or failed) it will be deleted.

In general if rendering fails it would be good to know what effects are used in the project. Sometimes the error is something like "error writing video frame: -28" (as in the original report) in this case it would be good to know what at the frame is (transitions, effects on clips,…)

Well, I don't have more messages, it's all I have (cf screenshot). So maybe my issue is different from the reporter. Do you know how I could grab more informations?

I don't use any effect in my shot: I just drag&drop the file, and render. Can't be more basic, and I guess you can see if from the attached kdenlive project. I tried with several files, the render always crash (even if it seems that the output file is usable).

I am not able to reproduce with the provided files. If you are still experiencing this please comment in bug report 447854 since it is similar but with more debug information.

*** This bug has been marked as a duplicate of bug 447854 ***