I've been creating and uploading images to the "featured image" in blog posts the same way with no problems, but am suddenly getting an error message. It reads, "Image upload failed. Could not generate an image extension name." The files sizes are small (around 144 kb), are jpegs, and have the .jpg extension already. I haven't been doing anything differently. Is this a bug? Is there a workaround?
A few minutes ago I talked to Shopify support and they suggested uploading the image with a Full Access account (my account had limited access).
So, I tried in the same store with a full access account, and it worked. The error does not appear.
I suppose for many it's not possible to have full access because of company policies, etc.
But at least, it's a temporary solution while it's being solved for users with limited access.