Downloaded mp4s from phone are corrupted!

[JJoffee]

I uploaded a lot of mp4 videos from my phone to my Dropbox account.  Now when I download them back to my phone to edit, they will not open in editing software.  (I use YouCut, but I've tried some others, too, and nothing works!)  Either the in the process of uploading TO Dropbox or downloading FROM Dropbox, something happens to the file.  I'm sick about this, since I have a number of irreplaceable videos in my Dropbox.  I have a few videos stored in Google Drive and this does not happen when I upload/download videos there.  I might have to switch to Google Drive.  In any case, I hope I can get the mp4s already in Dropbox to work properly.

[Nancy]

I’m sorry to hear this, @JJoffee. 

Do you remember if you uploaded these videos manually the first time, or via camera uploads? 

Was the uploading process interrupted for any reason at all?

If you try to preview the videos on your Dropbox account instead, do you receive any errors? If you do, please send me a screenshot of what you see.

Keep me posted.