Sorry, this type of video cannot be saved to this device

Good to know.. is there a way to fix this? it just doesn't add up to me because I've used dropbox for years now, with the same camera, same file types, same sizes, same sd cards etc. nothing changed. So why all of the sudden this issue? I filmed a few days after again not even in 4k and it's still the same issue. it's unfortunate. It's not just me, my phone is updated, dropbox is updated, I have storage and I've sent it to 4 people purposefully to see if it was just my IOS device and its not. Everyone gets the same message. I NEED a file sharing service. Ive used dropbox for so long and it's been a vital part of my business but if my clients can't download their footage have to go somewhere else.

I'm not sure, I can look into this more if you can provide an example video that doesn't work (and if you'd like, an example video that does work). The system doesn't tell us why a video can't save, just that it's not valid for the photo library.

Hello to anyone having this issue, where a Premiere Pro exported .mp4 video file will not save to your iPhone, and particularly when saving from DropBox. I have root-caused 2 contributing factors: 1. Exporting using 'hardware' and not 'software' under the 'performance' setting can cause the problem. 2. I found a 6k aspect ratio also caused the issue - when I reduced the export aspect ratio to 4k or below, the file saved to the iPhone as expected. I hope this helps someone.