Currently it seems like the debugger source list displays the last source in the list first, which happens to be from an addon, and the source fails to display. Perhaps the error is what makes it go to that source...? Anyway, we should always aim to prefer opening a source from the main page, not from addon. STR: 1. Install the 1Password 4[1] addon 2. Go to the test page[2] 3. Open the Debugger 4. See that the last source (from the addon) is selected ("javascript:self.on("click", function (node, data) { self.postMessage({'name':'click', 'data':node}); });") Also, the source view contains the following error: Error loading source: Could not load the source for javascript:self.on("click", function (node, data) { self.postMessage({'name':'click', 'data':node}); });. [Exception... "Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIChannel.asyncOpen]" nsresult: "0x80040111 (NS_ERROR_NOT_AVAILABLE)" location: "JS frame :: resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/devtools/server/main.js -> resource://gre/modules/devtools/server/actors/script.js :: fetch :: line 5380" data: no]Line: 5380, column: 0 [1]: https://agilebits.com/browsers/index.html [2]: http://people.mozilla.org/~schien/test_ssdp.html

Strange, my experience of the debugger is that it jumps to the first source first so maybe as you say it is because this one is broken somehow. In general do we expect javascript: scripts to display in the debugger at all?

Using Debugger.Source on the server (bug 905700) should let javascript: URLs to appear as sources.

Sounds like bug 905700 will fix this then