Impossible to recover after crash

[piiskop]

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 20.10
Release: 20.10
Codename: groovy

Shotcut version 21.05.01

I was working on an MKV-file for some hours using just one track and the file has the resolution of 1280 * 720 px. The other time I triggered undo the application froze. I waited many minutes and returned to the computer for discovering that the application was closed. I reopened it. I clicked the project name I was editing before the crash and chose to recover the project. The first frame of the file appeared however the timeline and playlist were empty. I opened MLT-file in emacs and saw that it missed all the huge amount of changes I had made to the project. This time, I killed the application and reopened it following by opening the same project. Instead of the first frame, INVALID was displayed. I also had a look at the recovery folder and it contained nothing useful. Shotcut just destroyed everything I did during these hours. This isn't acceptable. In addition to this case, I have three other projects that are impossible to reopen. This all can render Shotcut useless as similar things happened to Kdenlive that led me to stop using it. I went over to Blender before I discovered Shotcut. I've made many successful projects with Shotcut however these four unsuccessful projects describe the application as not trustworthy. An app should not destroy anything however Shotcut does sometimes. You can blame melt or something else, I don't know, for me as an end user, Shotcut is responsible for the fail of these four projects. I also add the current MLT-file that has not much useful information in it anymore and the application log if that can help you tracking down the reason for these deletions.
crash.txt

matemaatika-daliaga-20210310-nurgavõrrandid.zip

[ddennedy]

Sorry but I was not able to reproduce it. Your project file is empty:

<?xml version="1.0" standalone="no"?>
<mlt LC_NUMERIC="C" version="7.0.0" title="Shotcut version 21.05.01" producer="playlist0">
  <profile description="HD 1080p 25 fps" width="1920" height="1080" progressive="1" sample_aspect_num="1" sample_aspect_den="1" display_aspect_num="16" display_aspect_den="9" frame_rate_num="25" frame_rate_den="1" colorspace="709"/>
  <playlist id="playlist0" title="Shotcut version 21.05.01">
    <property name="shotcut:projectAudioChannels">2</property>
    <property name="shotcut:projectFolder">1</property>
  </playlist>
</mlt>

When a project is recovered from an auto-save, it does not automatically overwrite the original project, and you should not save it until you have verified the recovery. It sounds like you did that and only lost your unsaved changes, but as a reminder. Please be aware that version 21.05.01 has a major bug in it when you use File > Open MLT XML or open an old project that used that, or when you use as Clip or Copy Timeline to Source and try to Export. Unfortunately, not enough people tested our alpha and 2 betas leading up to this version.

In your log file I found the interesting message:

[Warning] MltXmlChecker::checkIncludesSelf This project tries to include itself; breaking that!

We have tried to prevent people from doing this interactively, but it seems you have somehow bypassed those checks. Maybe this combined with the including MLT XML file bug above mentioned above combined to produce your problem. Also, it looks like there could be something wrong when it must repair (as required for the problem it found) an auto-saved file. I do not think that is tested well.

[piiskop]

I explain my process in more details:

1. I created a new project.
2. I opened MKV-file that started to play right away.
3. I moved that file from step 2 to playlist.
4. I copied the file from step 2 from the playlist to the timeline. This has been the only file used in the timeline.
5. I started linear editing by cutting out silence, moving pieces together by slightly overlapping them to create fading effects. I never saved the project. My linear editing was an ongoing process for some hours. Sometimes I undid some cuts or moves. Then, it took a while until the software became responsive again. MKV-file's duration is about 90 minutes. Once I had cut out about an hour and only about two last minutes were left to edit, I undid a cut. This brought the software unresponsive again and it never recovered from that. It was just closed some minutes later.
6. I reopened the software.
7. I clicked the project created in the step 1. The software asked me to decide whether I want to recover.
8. I clicked to the button of recovering.
9. The software showed only the first frame and nothing on the playlist nor timeline. As I checked MLT-file it only had about 20 lines and nothing about my linear editing.
10. I killed the software and wenth through the steps 6 - 9 again. The only difference this time was that even the first frame wasn't shown but only white INVALID on the black background.

I didn't use Copy Timeline to Source. I never reached exporting the final product.

I dodn't know what the message about project including itself means as the only file I used was MKV-file.

I would record the whole editing process next times for the case it might happen again.

[piiskop]

It happened again.

[ddennedy]

I watched the video, and I can see that the autosave saved a reference to a temporary MLT XML file in the autosave folder in the same manner as File > Open MLT XML as Clip, which is similar to Copy Timeline to Source. FYI, when you get that "The project has been modified" dialog at close and you are unsure, I suggest to Cancel and use File > Save As to save it as a different name. When you saved and reopened it shows INVALID because it was now referring to that temporary file in autosave that no longer exists.

I have not figured out why yet, but I am making this note as my key finding from the video for future reference. Thanks for making the screen recording.

[crazcalm]

I ran into this issue as well. I do not know how to reproduce it, but I can add some extra information.

Shotcut crashed while I was exporting a file. When I tried to re-open the project, I ran into the same issue as @piiskop.

The new information I have is that when I tried to open other shotcut projects that where unrelated to the crash, most of the newer projects also would not open. However, when I went back to a project that is a little over a month old, that project opened.

Sorry I couldn't be more help.

Thank you for all the work you put into this project! I have been using Shotcut for years now and I will continue to do so!

[piiskop]

I just tried to reopen a project, I had been working on in March. The status bar just says that Shotcut is opening the project however it takes forever. The application doesn't crash but the whole computer system is influenced and even mouse cursor is barely movable. It lasted some hours until I killed Shotcut. After that, even Chrome was frozen and not killable.
matemaatika-patrikuga-20210801-ristküliku-kolmnurga-trapetsi-lahendamine.mlt.txt
This also happend to open-transport-tycoon-deluxe'i-klubi-20210222.mlt.txt.