Photos Sync error - some .mov files "cannot be played on this iPhone"

> When I sync my iphone to my MacBook Pro

I assume you meant some movies can not be synced from the Mac to the iPhone, right?

You can search the movie via the Terminal. The following example assumes the Photos library is in your home folder in Pictures folder. Replace your '93B94BB0-433F-4423-82A1-D02F13C209E6.mov' for the movie's name in the next command...

find ~/Pictures -name '2D552696-608B-4CE0-9B3F-BF2E6DBA00B4.mov'

...the result is something as follows:

/Users/matti/Pictures/Photos Library.photoslibrary/originals/2/2D552696-608B-4CE0-9B3F-BF2E6DBA00B4.mov

...use that string to open and check the offending movie in QuickTime Player so you might then be able to identify it:

open '/Users/matti/Pictures/Photos Library.photoslibrary/originals/2/2D552696-608B-4CE0-9B3F-BF2E6DBA00B4.mov'

Obviously the offending movies have some codec that the iPhone does not support. A workaround is to re-encode such movies (with Handbrake, Shutter Encoder, ffmpeg etc) to plain H.264/H.265 video and AAC audio wrapped as .mp4.

Video formats are flaky. Just because it says ".mov" doesn't mean it's the same as another ".mov" format. Older files are especially troublesome. 32 bit videos, made before the world turned to 64-bit systems, may be unreadable.

Photos does not use filenames like "IMG_0123.mov," which could be used by several different files. Rather, Photos changes the filename to long but unique codes, and then remembers the old name in its database. When the file is unrecognizable, there may be a problem connecting the original file to the thumbnail.

I have a number of videos that I converted to newer formats, but I also have a number of videos that are just past saving.

You may be able to use a Smart Album with

to find broken files. It doesn't always work. It may catch some but not others.

The best way to separate out the videos that don't work is to synchronize the Library with iCloud.com. Only the good ones will be synced. That might coast a couple of bucks for a month's subscription, but it may be easier than trying to find the bad ones.

What do you think?

Matti suggests how you can find the crazy picture files. Notice that the location he finds is in inside the Photos Library package. It's a package not a file, meaning it's a folder that you are not meant to enter. If you were to delete the file you find, for instance, or change it a bit, it may totally corrupt your Photos Library. The general rule is "NEVER EVER mess around inside the Photos Library." If you want to play, be sure you do it with a COPY of your Library so you don't have tearful regrets!

By the way, if you don't like using Terminal, the app Find Any File ($6) would find the file inside the package. I purposely avoided mentioning this. Spotlight doesn't search inside the Photos Library package, since you are not intended to mess around in there.