How do I deal with the "App Preview is too large" error in App Store Connect?

Question

I'm having trouble uploading App Previews in App Store Connect. Despite following all of Apple's specifications, App Store Connect rejects the file with messages like:

• "Your app preview is too large" (despite it being way below the max size of 500MB)
• "The dimensions of one or more previews are wrong" (despite them being correct)

This happens either as soon as I start uploading the file or after it has finished processing.

It also happens for both supported formats: H.264 and ProRes 422 (HQ). I have tried using about 10 different export presets for the file, and even tried re-converting my (already compliant) video editor output with ffmpeg, but no luck.

Answer 1

AppStore Connect often gives the wrong error message (as of March 2021). First, make sure that:

• Your video file really is 886 x 1920 (for 6.5" phones) or 1080 x 1920 (for 5.5" phones). The former is especially tricky, because screen recordings coming from those devices are 888 x 1920 (i.e. 2 pixels wider).
  • Yes, you'll get the "dimensions [...] are wrong" message even when the resolution is correct. See below for what to do in that case.
• Your video file is less than 30 seconds long, as per specification. Even one frame over 30 seconds will get the video rejected, and the error message will say "too large" (not "too long").

Once you know the above is not the problem, I recommend going with iMovie export (official docs). iMovie is free, comes with every Mac, and has a built-in App Preview export capability.

1. Whatever you use for editing your App Preview (Premiere, After Effects, HitFilm, etc.), export the video in high (maybe even lossless) quality.

2. Open iMovie.

3. File > New App Preview.

4. Drag & drop your video file into the iMovie window, and then into the timeline.

5. Click the export icon (hidden in the top right corner of the iMovie window)

   

6. Select "App Preview"

7. Export the video

It's unclear to me how exactly iMovie encodes the video, but it works.