Exported slideshow MP4 file not compatible with Quicktime or Mac Photos

[abqc]

I have created numerous slideshows in LRC with music and successfully exported them as MPEG-4 files. However, I now find that they will not open in Quicktime or Mac Photos. The manual states that LRC saves them as H.264 MPEG-4 files, and that they can be opened in Quicktime and Photos, but the attached error message says otherwise.

[Sean McCormack]

Just did a quick test using an MP3 for the music, exported to 1080p and the result plays in QT.. I'm Monterey 12.6.2 though. 

[johnrellis]

I did a quick test on my LR 12.3 / Mac OS 13.4 -- I exported a 1920 x 1080 slideshow as a .mp4, and it plays in Quicktime without issue.

To narrow down your issue:

1. Please do the LR menu command Help > System Info and copy/paste the entire contents here so we can see exactly which versions of hardware and software LR thinks you're running.

2. Make a very short slideshow .mp4 with the problem and attach it to your reply here.  

[abqc]

I attach as requested a screenshot of the system info. 

I have made a short slideshow but this one opens ok in Quicktime (attached).

Of the two previous ones, one now opens in Quicktime and the other still does not. I attach the error message for the one which does not.

[Sean McCormack]

The test slideshow plays fine in Quicktime here. 

[johnrellis]

"I have made a short slideshow but this one opens ok in Quicktime (attached)."

It would help to see one that doesn't play on your computer. If it's too big to attach it here, upload it Dropbox, Google Drive, or similar, and include the sharing link here.

[johnrellis · Accepted solution]

Also, just to verify, have you restarted your computer?  LR's helper apps (which run in background) for making videos are a little flaky.

[abqc]

I have restarted my computer and have exported the slideshow which would not work before. It now does work, so I think this issue is resolved. Thanks for your help.