I can't reproduce this locally, but worked with Nate (cc'ed) who could to narrow this down to the call to `yield DebuggerClient.socketConnect` here: https://searchfox.org/mozilla-central/rev/74b7ffee403c7ffd05b8b476c411cbf11d134eb9/devtools/client/framework/toolbox-process-window.js#47. We suspect this has something to do with no prompt showing up despite `devtools.debugger.prompt-connection` being true. Still need to do further debugging but I suspect the issue can be reproduced locally by returning a promise that doesn't resolve inside that function. A couple other things we could do while we are here: 1) Convert toolbox-process-window to use async/await instead of Task 2) Provide some feedback in the UI on where in the connection process the Browser Toolbox is to make it easier for us to debug problems like this (i.e. show a message before each step in the connect function)

I have same problem under Linux - just an empty window.

(In reply to drJeckyll from comment #1) > I have same problem under Linux - just an empty window. Do you see a prompt asking for permission to connect when you open the Browser Toolbox? And what is the `devtools.debugger.prompt-connection` pref set to?

(In reply to Brian Grinstead [:bgrins] from comment #2) > (In reply to drJeckyll from comment #1) > > I have same problem under Linux - just an empty window. > > Do you see a prompt asking for permission to connect when you open the > Browser Toolbox? No > And what is the `devtools.debugger.prompt-connection` pref > set to? devtools.debugger.prompt-connection: false It's Firefox 60.0a1 (2018-02-20) (64-bit) under Gentoo Linux

It doesn't seem to me that we have enough data about the actual issue here yet... For now, I've focused on improving the connection status in hopes of getting more info.

Comment on attachment 8952640 [details] Bug 1438962 - Convert Browser Toolbox window to async / await. https://reviewboard.mozilla.org/r/221886/#review227868 Thanks!

Comment on attachment 8952641 [details] Bug 1438962 - Add diagnostics during Browser Toolbox startup. https://reviewboard.mozilla.org/r/221888/#review227874 This will definitely help. We can ask Nate to re-test once this hits Nightly and spin off a new bug based on what status messages we see. ::: commit-message-8cab6:1 (Diff revision 1) > +Bug 1438962 - Add diagnostics during BT startup. r=bgrins Nit: "BT" -> "Browser Toolbox" ::: devtools/client/framework/toolbox-process-window.js:34 (Diff revision 1) > > var gToolbox, gClient; > > -var connect = async function () { > - window.removeEventListener("load", connect); > +function updateStatusMessage(msg) { > + let statusMessage = document.getElementById("status-message"); > + statusMessage.value = msg; I could see it being useful to append the status messages instead of wiping it out at each step so we could go back and get the connection details or other info when debugging an issue from a bug report.

Comment on attachment 8952641 [details] Bug 1438962 - Add diagnostics during Browser Toolbox startup. https://reviewboard.mozilla.org/r/221888/#review227874 > I could see it being useful to append the status messages instead of wiping it out at each step so we could go back and get the connection details or other info when debugging an issue from a bug report. Good call, changed it to append instead.

Pushed by jryans@gmail.com: https://hg.mozilla.org/integration/autoland/rev/38c6b0c07b2a Convert Browser Toolbox window to async / await. r=bgrins https://hg.mozilla.org/integration/autoland/rev/6fd6890d798f Add diagnostics during Browser Toolbox startup. r=bgrins

https://hg.mozilla.org/mozilla-central/rev/38c6b0c07b2a https://hg.mozilla.org/mozilla-central/rev/6fd6890d798f

Today build - in browser toolbox I can see only: Connecting to localhost:39243, ws: false