If anyone wants to know, I finally figured this out after how long? The TouchBar has a man page button above the "2" key and it is easy to hit that when you try to hit one of the keys below it. You can use View menu in Terminal/Customize Touch Bar to drag that virtual button off the touch bar.

Yes I have seen notes about this behavior in Stackoverflow etc. Thanks for the response! Do you know offhand if it is allowed to run the AVAssetWriter from a true background process: BGTaskScheduler? Apparently those allow more time than the app just going off into the background. Another alternative might be a software implementation of an MP4 writer that takes an AVAsset as input. Something like ffmpeg or something. Not as efficient, but pausing due to app sleeping might be less of an issue then.

Note: this seems to have been fixed.

if anyone else is running into this error, just ran into this in Feb 2021, i found a clue that helped me solve it via this other forum post https://developer.apple.com/forums/thread/662300 when i would go to the keychain app on mac and click on the auto-generated developer certificate (not provisioning profile, but certificate), keychain was showing a message about the certificate being "not trusted" delete that cert, it seems to be bad. this led me to the above link, which tells you to re-download an intermediate certificate. then do the automatic provisioning in apple xcode as usual (like unclick automatic button and reclick it). then try to run on device. works, finally first time in a couple weeks i got this to work. what a terrible error message it gives for this problem. why not just say the intermedidate certificate is untrusted, so get a new one from this link here?

hi, thanks for the response. the problem seems to be at some low level. example case is: get a movie longer than 1 hour into your camera roll. try to clip it to 1 hour with the built-in video tools in the iOS photo app. it clips it to something like 43 minutes instead of 1 hour. we have temporarily worked around the problem by only allowing 40 minute videos max in our app. it is interesting that you say there might be a problem w/ the video, i will try other videos when we get back to this issue.

thanks for the clarification about how DSYM works w/ bitcode. we typically disable bitcode on upload.

strange, we are having the opposite problem, videos not playing in wkwebview on ios14.8 but working properly in ios15

continued: this is the error we get fairly often (same file works other times). this is a file from the photos folder. Error Domain=NSCocoaErrorDomain Code=260 "The file “IMG_2685.mp4” couldn’t be opened because there is no such file." UserInfo={NSFilePath=/var/mobile/Media/DCIM/102APPLE/IMG_2685.mp4, NSUnderlyingError=0x281af1cb0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}}

update: user can now download the app (we get the download progress meter and it proceeds) but the app disappears immediately after download and instead of the Open button showing in test flight, it goes back to the Update button. so still no-go.

the AVMetadataItem writing indeed seems fraught with peril. i tried a bunch of examples with basic stuff like title and description in the "common" metadata family, and none of them seem to write data to the file using AVAssetWriter for mp4 files. checked by mpls command line. does anyone know the difference between the .key and the .identifier ? i see examples with .key and examples with .identifier. why we should use one over the other = ?

now the test flight downloads seem to be working again. strange.

We would also be interested in the answer to this, e.g. if the 3 packages have the same or similar functions, which is faster on which devices.

FYI to Apple: getting a big red X and "request timed out"

update: binary upload just worked. it failed several times this morning with aforementioned request timed out.

note: we traced what was causing this, if any one sees the Cannot Open error. It was a zero length cached version of the mp4 file.