HTTP Error for media uploads, but images accessible by URL

Hello, when I upload a group of images into the Media Library, several of them invariably throw an ‘HTTP Error’. However, everything uploads successfully; I can see the filename, but no thumbnail. If I click on the attachment and then go to “Edit More Details,” I can see the image. I can also access the file directly via the URL, and it will show up on the front end when inserted in a post.

This always happens with the same files. I’ve even run a group of files through ‘Export for Web’ in Photoshop, and it’s always the same files from the batch that fail in this way.

I have turned off all my plugins, and it did not change anything.

Any advice would be greatly appreciated!