Your applications user agent is incorrectly configured.You are using an outdated program that makes use of bad practices or old API endpoints.You have not updated your application to use the new API urls and response formats.
There are a few different reasons that you can run into this message: It's great, and probably does what you want!
403 Access Denied - Oh no! If you were using a script/program you found to try and download content, it's likely that the script was what resulted in your request being blocked.