STR:

1. Try to open Browser Toolbox using: Tools -> WebDeveloper -> Browser Toolbox

No window opened, no error in the system console/browser console

This happens in every new Firefox profile I create after some time (no extensions installed). I am usually forced to create another profile to get the Browser Toolbox working - since trying open it repeatedly doesn't help. Using that same broken profile next day often works.

There is nothing in the system console, but flipping this pref:

devtools.debugger.log

...can help to see more about what's happening.
(even if I didn't see any helpful error there)

See also:

• Bug 1371548 - No Browser Toolbox
• Bug 1374837 - Browser Toolbox still not working in Windows 7 or Windows 10 in a local build

(Maybe commenting out the line in this bug, could help)

Honza

Getting below error in windows 10 while accessing multipurpose browser devtool using Ctrl+Shift+Alt+I

DevTools Server for Browser Toolbox listening on port: 62725
Starting Browser Toolbox c:\mozilla-source\mozilla-central\objdir-frontend\dist\bin\firefox.exe -no-remote -foreground -profile C:\mozilla-source\mozilla-central\objdir-frontend\tmp\profile-default\chrome_debugger_profile -chrome chrome://devtools/content/framework/browser-toolbox/window.html -purgecaches
Assertion failure: false (MOZ_ASSERT_UNREACHABLE: Opcode sequence includes commands after JMP), at /builds/worker/workspace/obj-build/dist/include/mozilla/interceptor/PatcherDetour.h:895
JavaScript error: , line 0: uncaught exception: Object

I don't know what the problem is but, bug 1615412 might be related.

Honza

(In reply to Shashikant from comment #1)

Getting below error in windows 10 while accessing multipurpose browser devtool using Ctrl+Shift+Alt+I

DevTools Server for Browser Toolbox listening on port: 62725
Starting Browser Toolbox c:\mozilla-source\mozilla-central\objdir-frontend\dist\bin\firefox.exe -no-remote -foreground -profile C:\mozilla-source\mozilla-central\objdir-frontend\tmp\profile-default\chrome_debugger_profile -chrome chrome://devtools/content/framework/browser-toolbox/window.html -purgecaches
Assertion failure: false (MOZ_ASSERT_UNREACHABLE: Opcode sequence includes commands after JMP), at /builds/worker/workspace/obj-build/dist/include/mozilla/interceptor/PatcherDetour.h:895
JavaScript error: , line 0: uncaught exception: Object

This seems very similar to bug 1586741, which I see basically every day or so.

This is likely fixed by work done in Bug 1120863 - Browser toolbox starts blank and doesn't function with pending updates
Feel free to reopen if you are still experiencing this issue.

Honza