A thread like this is off-topic for Google Groups, and should be posted to StackOverflow. While I'd like to help you, this isn't the place to do it. This forum isn't meant for specific 1-on-1 technical issues, but for general discussion of the platform and its services. With StackOverflow, which we also monitor, you'll be in touch with a much larger user-base of people who are going to help you, and in a format which is designed for that purpose. Check out our community support page for the list of tags we monitor.
You can check this thread which discusses how to remove file extensions on URL. Or this thread that has a user with similar issue of not fetching the images after removing the file extensions.