Turning off iCloud sync w/ Photos on Mac threatens to delete local files A while back I elected to start syncing my Photos on my Mac to iCloud.  I quickly ran out of cloud storage (5GB).  I have decided I don't want to deal with some of the back &amp; forth confusion between my computer &amp; iCloud.

In Photos > Settings, under the iCloud tab, when I attempt to un-check iCloud Photo Library, a message comes up saying "Your iCloud Photo Library is currently updating."  (This makes no sense - the library has long been full).  This message has two options, "Turn Off" and "Continue Updating".  Checking "Turn Off," brings up a rather disconcerting message: 1,250 low-resolution items will be removed from this Mac. Full-resolution versions will remain in iCloud.  So my question is, why would turning off iCloud be cause to remove items from my computer?

Help is much appreciated,

Max

edit:  running OSX Yosemite 10.10.5
You enabled a feature called "Optimize Mac Storage" where low-res photos will be stored locally on your Mac, but the original resolution photos will be stored in iCloud. So when you are disabling sync, iCloud choses to delete the low-res photos on your Mac, and keep them in iCloud.

Method 1: Contact Apple support, or walk into an Apple store and ask them for help.

Method 2: Try finding and disabling the feature I mentioned in the first paragraph. The alternative is called "Download and Keep Originals. This will only work if you have enough space on your device. After you disable that feature, disable iCloud Photo Library

Method 3: You should try downloading all the photos currently stored in iCloud and put them in the same (create a new folder) folder as the ones that have not been uploaded (make sure they are original resolution, as a back up). Make sure there are no duplicates. The number of photos should add up to the total number of photos you had(2,073 in your case). Then just disable iCloud Photo Library. Then just delete all the photos in your Photo Library, and put all the pictures that in the backup you created earlier into your photo library.