The error Failed. Response code = 500. Response message = Internal Server Error occurs when Shopify is NOT accepting the image upload.


The error is caused by Shopify. You may check this by going to Shopify Admin Page:

Product > Choose A Product > Media > Add Media From URL >
input: Image URL

We are not sure why some images are ok. We can do is set up Image CDN to load the images. 


Solution:


We are not sure why some images are ok. We recommend to setup Image CDN to load the images. You can refer here for the setup.