Cannot import photos from iPhone
If I plug my iPhone up to my iMac and try to import the photos from the phone to the computer, I get a cannot import error. It says they may be an unrecognizable format or may not contain valid data. I attached a photo of the error. iOS 11.2, macOS 10.13.1, Photos 3.0. I also tried importing from my wife's iPhone 6 into her photos library and got the same result. Some photos imported just fine, many will not. I even took random photos after rebooting the computer and phones and tried again with the same error on the just taken photos. Any ideas?
IMAC (RETINA 5K, 27-INCH, LATE 2015), macOS High Sierra (10.13.1)