Closed Bug 1530861 Opened 5 years ago Closed 5 years ago

Blank Debugger panel when using remote debugging


(DevTools :: about:debugging, defect)

Not set


(Not tracked)



(Reporter: jdescottes, Assigned: ochameau)




(2 files)

This is a backward compatibility issue from Bug 1269919


  • devtools.toolbox.selectedTool should be set on the client
  • client should have Bug 1269919
  • server should not have Bug 1269919


  • open DevTools
  • select a Panel
  • close DevTools
    (the goal of this step is to set the pref devtools.toolbox.selectedTool, which triggers the bug for some reason)
  • open about:debugging-new
  • connect to your older server
  • inspect any tab
  • in about:devtools-toolbox, select the debugger

ER: Debugger UI should display
AR: Debugger UI is blank

The UI crashes because listWorkers doesn't return a workers array:

Note that simply doing

  let { workers } = await tabTarget.listWorkers();
  workers = workers || [];

at "fixes" the issue.

Alex, looks like is breaking backwards compatibility, or at least it bricks the debugger UI. Any idea why this would happen? At first glance, I don't understand why this patch would impact a listWorkers() call?

Flags: needinfo?(poirot.alex)

Thanks for the report, it is a pretty trivial fix.
I never removed an event and it needs special care to not break backward compat.

Assignee: nobody → poirot.alex
Flags: needinfo?(poirot.alex)

newSource events used to be sent on the target actors on FF66 and before,
this is no longer the case. But we still have to accept them if we connect
to old remotes, otherwise the events are considered as a method reply
and confuses packet ordering.

Pushed by
Acknowledged newSource events sent by remote devices on FF66 and less. r=jdescottes
Keywords: leave-open

thanks for fixing the comment in a followup :)

Closed: 5 years ago
Keywords: leave-open
Resolution: --- → FIXED
Pushed by
Fix typo in deprecated firefox version comment. r=jdescottes
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