If so, then something in your web pages is requesting that file, and App Engine can't find it within your application. Specifically, a
min.map file is a sourcemap: someone is looking at your web pages with Chrome's developer tools or similar. You can find the map file and place it in your application,
see the details of how to do this here. Note this: Normal users will not need the sourcemap data, it's only needed for debugging JS code via development tools.