I'm using a third party image cloud service. After some days back, I got this error. The Domain and image path are different. How do I fix this?
That error relates the Googles Carousel Rich Snippet. As you are marking up an ItemList your markup relates to that:
The way you marked it up comes under the "Summary Page" structure which has the restriction:
All URLs in the list must be unique, but live on the same domain (the same domain or sub/super domain as the current page).
Further reading of the guide and you will find out that the url should refer to another page that contains structured data for a supported type of entity. An image url is not a supported type of url.
If you have no interest in the Google Rich Snippet, you can ignore the error.