That could be the case of an invalid/broken image link.
You can follow the below steps and debug this error you are facing.
STEP 1 - Upload in any Online free image hosting service
Visit https://imgbb.com/ > Click on ‘Start Uploading’ > Browse and select your image file > Click ‘Upload’ (Avoid Google image links)
STEP 2 - Open the link, and Copy the Image link
STEP 3 - Paste the link on the Edit page
Your issue could be most likely because of a broken URL. Make sure the link has an image format (like jpg, png jpeg) at the end of it.
If you face any issue in any step, or have any queries, do let me know.