I've edited an MP4 movie file in Quicktime Player Version 10.5.

When I try to save the edited file, I get: The operation could not be completed.

Does anyone know what causes this and/or how it can be solved?

macOS Mojave 10.14.2 / Quicktime Player 10.5 / MacBook Pro (Retina, 13-inch, Early 2015)

  • I have the same problem. Found out later the error code is "-12769".
    – kitta
    May 4, 2019 at 5:36

7 Answers 7


For me, the error came as I was editing in Quick-Time by right-clicking on the imported video in the Photos app.

Once I dragged the video (export) to a directory, and then edited the .mp4 file, all was fine. No errors when Trimming and Saving.

  • Photos.app already supports trimming videos and can do a lot more. There’s no point in using QuickTime here.
    – fregante
    Apr 8, 2022 at 8:25
  • The original post was about using QuickTime... So I thought this might be a useful bit of evidence for the OP to get something working. But thanks (?) for pointing that QuickTime is not needed, @fregante. Maybe you should make that an answer instead of a comment to my answer?
    – Jon Kern
    Apr 10, 2022 at 19:43
  • I can't seem to get photos to edit the video, i just need to trim it
    – Shanimal
    Sep 10, 2023 at 1:55

I had a similar problem when I downloaded a youtube video, opened in Quicktime to "trim" the video and quick time would not complete the operation. I ran the youtube video through Vlc Crunch (free video converter)as mp4 again and then Quicktime worked fine.

  • 1
    The point of using QuickTime is to avoid downloading other software. If you must use other software, just find one that allows trimming too. Saving the video from two apps makes it lose quality.
    – fregante
    Apr 8, 2022 at 8:24

I found a workaround. It seems that QuickTime is able to handle the file via the Share feature but not the Export.

You can choose to share to Messages and then save the file from there, or use Shareful, a small free app that lets you enable a "Save as" option in the Share menu.

Share -> Save As…

  • There was a time when these kind of discrepancies where unthinkable in Apple software … Thanks though! Apr 5, 2022 at 12:34

Guyz hello, i'm on High Sierra, i have that error "The operation could not be completed / Impossibile completare l'operazione", it happens often when i trim / cut a downloaded .mp4 video(same happened on el capitan), i think it cause there are small problems/errors after the download of a video, also if video is well played by Quick Time / VLC. So i simply copy the downloaded video and paste it in another location, example - copy from download folder and paste to desktop. Then i can save the trimmed / cutted video. I think after copy in some magic way OSX corrects those small errors. Hope it will work for you also! Have a nice day!^^


Not an actual answer. But inform some important piece of information.

I encounter the same problem. The error code is "-12769"

Found out that there are some input videos which worked.

And when I compare both info of videos.

A video that's work :

Good video

A video that's doesn't :

Bad video

The only difference is encoding software between Lavf57.19.100 vs Lavf58.12.100

  • Have you tried more samples to make sure this isn’t a coincidence? You’d need a lot more samples, really, from a lot of different sources. There is more to a video file than what shows up in QuickTime’s Get Info pane. :) Mar 28, 2021 at 1:14

I get this error all the time as well (usually with error code -12780). I have a feeling it is related to files that have small errors (like missing keyframes, or a videotrack that is out of sync with the audiotrack).

Unfortunately the only solution i have found thus far is re-encoding the video and trying again (using a tool like ffmpeg or Handbrake) or using editing software like Premiere Pro / iMovie / Final Cut. In both cases, you need to re-encode the video and it will take some time.


This is an old question but I will answer it for others having the same issue. (Added note: I just realized my error is slightly different - it won't save because I don't have permission).
I just solved it by changing the folder it's saved to. It was defaulting to my Mac hard drive and for some reason would not save there. I changed it to another folder and it saved just fine. Hope this helps someone.

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