there was an error downloading this photo from your iCloud photo library

I agree. Its because they’re basically a monopoly and can do whatever they want

Thanks for this simple, valuable assistance.

I could kiss you!!! I've been going crazy wondering why they download sometimes and not others. Thank you!!!!!

I can’t believe this was the reason lol thanks so much

Thank you!!! Wish I would have know this sooner!

Thanks, that was indeed the problem in my case. Why can't it tell you, instead of expecting you to spend hours trying to figure it out? (Rhetorical question).

Omg that was the problem!!! Thank you so much

Thanks mate. This worked in my iphone 6S. Now all pictures that had download error is error free now. Bunch of thnx

For folks who are saying your photos disappeared when you signed the device out of iCloud, have you tried going to

iCloud - Sign in

on a desktop with lots of free storage? (My desktop is a Windows machine and it works fine, so I suspect it will work on anything, i.e. you don't need to have a Mac to try this.) You can use the same ID and password as you use to sign in to iCloud on your iPhone/iPad. My photos all show up there.

The reason I'm suggesting this is, I'm wondering if your troubles on the iPhone/iPads is that your storage on those devices may be low? If that's the problem then you can at least reassure yourself that your photos are fine by viewing them on your desktop.

I think the only way photos can actually disappear from iCloud is if you delete them on your device while you are still signed in to iCloud. For example don't delete the photos and then sign out of iCloud. Sign out of iCloud first, and only delete the photos after you have signed out of iCloud.

This did not help my problem. I wish I could figure this out.

I'm having the same issue. Tried everything. Did you figure it out?

U just caused me to delete a bing of my photos and videos permanently thanks

If anyone is running into this issue in 2017 or later, it could also be due to your low battery setting being turned on

While this does help sometimes with getting some of my most recent photos to download, it doesn't always work, and is less consistent for my older photos.

I took a picture of some whiteboard sketches last week and I need them to work. I've tried accessing them 6 times over the last 3 days, at different battery levels each time, and I have yet to be able to get it to load. Unbelievably frustrating.

Very frustrating.

It’s 4/2018 and this problem seems to have been plaguing folks for a while.

I’m trying to edit photos in apps or even in the photos app to no avail.

Same situation as posted by others.

It’s a blessing we get the previews and store the original in the cloud. I have too many pictures to store all full res pics on my phone. Thank you for that. But I really need to be able to easily download them to edit as well as upload to slideshow apps (with ease).