When experiencing an error, you can have a look at the HTTP response header to get the error's details.
Here's an example of such an error. When trying to access the following link:
we'll see the following HTTP response header:
X-Cld-Error:Invalid fetch URL - not properly escaped
This is returned when the URL we're trying to fetch the image from includes special characters. In this case '?'. URLs must be escaped for special characters for fetching.
In this case, the solution is to either escape the '?' special character (by replacing it with '%3F'):
Or to fully escape the whole URL: