Today I tried to upload six images, each less than 500K, using jQuery. For each image, the UI returned a message of Error: true. I upload a handful of images in this manner every week without issue. I tried both Safari and Chrome to see if it was browser issue, but got the same results. I have a screen capture of the error messages, but there doesn't seem to be a way to attach them here.

Please review:
https://www.zenphoto.org/news/problems-with-albums-and-images/

Also check the permissions of the album folder:
https://www.zenphoto.org/news/permissions-for-zenphoto-files-and-folders/