Paul Sedovic finally has enough storage on his laptop’s hard drive by way of a new computer to keep all his images on the internal drive. However, when he went to import many thousands of images into Photos, some thousands failed with an error dialog labeled Unreadable Files. Next to each image appeared the label “Unable to get metadata.”
When I selected a few of these photos individually, I was able to successfully transfer them, but I know no practical way to move a few thousand photos one by one.
Paul isn’t alone with this problem. People have reported a similar issue dating back to 2015, sometimes with an import from a local drive and sometimes when transferring images from a memory card.Paul Sedovic
Photos or macOS sometimes can’t keep up with the pace of imports and generates these errors.
One possible explanation is that Photos is stressing the operating system’s ability to decode information as fast as it wants it, and this could be a bug in how macOS handles images in general or just in the import module in Photos. When importing from a camera card, using Image Capture apparently makes the problem disappear.(The article continues...)