If a mapped source is not available on the server, i.e. the "sources" property in the source map refers to a file that doesn't exist, then the Debugger currently shows the 404 response from the server in the source view. Instead of showing the server response, the missing source should be handled gracefully. I see two ways to achieve this: 1. Let the source view stay empty and handle the case as if the source were black boxed. 2. Show the minified source instead and handle the case as if no source mapping existed. Sebastian

Is this a duplicate of bug #1228496?

(In reply to devurandom from comment #1) > Is this a duplicate of bug #1228496? No, bug 1228496 is meant to add a notification message at the top of the Debugger panel when the source map could not be loaded. This bug is about what to show within the panel instead of the 404 response. Sebastian

(In reply to Sebastian Zartner [:sebo] from comment #0) > 1. Let the source view stay empty and handle the case as if the source were > black boxed. > 2. Show the minified source instead and handle the case as if no source > mapping existed. The new debugger takes option 2. If a source mapped file doesn't exist it allows you see and pretty print the original file ( see: https://github.com/devtools-html/debugger.html/pull/1937 )