Hi Philipp, Here is the list of installed software :

https://pastebin.mozilla.org/8913166

I have uploaded an image of the installed software as requested. Would be helpful if you allowed text and PDF uploads for listings as well as images as I had to stitch this together in an image editor.

In reply to assistance-multi, my installation was 49.0.1, so don't bother with that, the bug is still there and it hangs as well, like 49.0 did for you.

kevinherrmann said

Would be helpful if you allowed text and PDF uploads for listings as well as images as I had to stitch this together in an image editor.

kevinherrmann, you can use https://pastebin.mozilla.org/ to paste huge text files.

And OK for 49.0.1 : I've tested it too, does not work neither.

hmm, no striking similarities there (also not with a third user that i compared). are you running firefox in account with limited user rights?

Philipp, I have administrator rights on my computer.

does it make a difference when you right-click the firefox icon and run it as admin?

Same here, it is running in an Administrator account with full rights. I can't test what happens if you specifcally grant Admin rights as I have downgraded to a working version. But that is a totally inappropriate way of fixing software bugs to bypass security, so it might help investigate but should not be used by anyone as a fix as it would be exposing them and their computer to risk.

@kevinherrmann, we are still in troubleshooting & diagnosing mode. this wasn't meant as a permanent solution (well it didn't work anyway). the one other thing to try would be if it is possible to launch it in windows safe mode as fred has asked earlier. in addition i think it would be good when one of you could file a bug for this issue at bugzilla.mozilla.org so that the problem can get some developer attention...

I am sure we are well aware this will not affect all Fx49 64bit installs. Just posting to confirm it runs ok on my Windows 10 (pre aniversary update) using en-GB

After having restarted windows in safe mode with network support, I launched FF49 with the same result : nothing happens.

I have tried to start FF49 holding the shift key (still in windows safe mode) : same behaviour.

I will try to file a bug at Mozilla's bugzilla.

Here is the bug I filed on bugzilla : https://bugzilla.mozilla.org/show_bug.cgi?id=1305436

Thanks, assistance-multi, let's see if they find and fix the bug in Firefox 50...

Although philipp did not notice anything striking comparing installed software lists, I scanned yours and I do notice that we both have Chrome browser installed as well as Firefox and all the blurb about the new Firefox 48-49 (although 48 is OK) says it makes Firefox start using the same interface as Chrome for plug-ins and one of my pug-ins stopped working on the occasions Firefox did load as I reported (I then disabled it to ensure it was not the culprit).

If it helps my Google Chrome reports it is 64-bit v53 but, as it updates all the time, I cannot be sure this was the version when the Firefox problem occured.

Perhaps philipp would check if the third person he mentioned also has Chrome installed? Thanks.

If they have and as that is exactly the area of the changes in Firefox, as a developer of 30 years' experience, that's where I would look first! 90% + of the time a problem in previously stable software is where you just made the changes.

no, chrome wasn't present: https://pastebin.mozilla.org/8913243

philipp said

no, chrome wasn't present: https://pastebin.mozilla.org/8913243

I am having the same problem (see https://support.mozilla.org/en-US/que.../1140828#answer-921455 here)

My story:

• R48 works, R49 doesn't
• I have Chrome and IE installed and they both work fine
• R49 works if my PC is in safe mode

is the issue the same with firefox beta and other pre-release versions - https://www.mozilla.org/firefox/channel/#beta ?

if this started to happen consistently after a certain point in the firefox developement process it might help if you could run the mozregression tool from to pin that issue down to a particular change in firefox: https://mozilla.github.io/mozregression/install.html

I was able to get the developers to create 2 test builds. Each one removing a patch that potentially causes this bug. It would help out if any of you who are affected could test these 2 builds and report what happens. Thanks!

https://bugzilla.mozilla.org/show_bug.cgi?id=1305436#c10 1st build: https://archive.mozilla.org/pub/firefox/try-builds/archaeopteryx@coole-files.de-516caa78c3a85cf55f14acdf661d0d3dff5b4f1c/try-win32/firefox-48.0a1.en-US.win32.installer.exe

2nd build: https://archive.mozilla.org/pub/firefox/try-builds/archaeopteryx@coole-files.de-3d23b6dfd423f4dfef4dac906719720267d9fc6a/try-win32/firefox-52.0a1.en-US.win32.installer.exe

Hi Noah_SUMO, thank you for your attention. I tried the 2 builds but unfortunately, Firefox does not start. Still the same issue : firefox.exe process running, no Firefox window. I'll complete the bug information on bugzilla.

Thanks for testing assistance-multi. I have 3 more builds for you & others to try. With any luck, one of them solves the issue.

1st build: https://archive.mozilla.org/pub/firefox/try-builds/archaeopteryx@coole-files.de-de43d3a6855baf1af736936fcf45c6bf3d61a0c1/try-win32/firefox-48.0a1.en-US.win32.installer.exe

2nd build: https://archive.mozilla.org/pub/firefox/try-builds/archaeopteryx@coole-files.de-de49838ff94722e7a15204292f692f694651b6e3/try-win32/firefox-48.0a1.en-US.win32.installer.exe

3rd build: https://archive.mozilla.org/pub/firefox/try-builds/archaeopteryx@coole-files.de-379be27d0174e832bf221417ab1f40ffcac7d26c/try-win32/firefox-48.0a1.en-US.win32.installer.exe

Hi Noah,

I have tested the 3 builds, and the 3 have the same (surprising) behaviour :

Firefox starts, main window opens, but Firefox can't open any URL. The tab title shows "Connecting...", waiting forever. I've tried safe mode with the same result. Exitig Firefox (File/Exit) does not work : the window closes, but firefox.exe process still runs in background, I need to kill it manually, which sometimes results in a crash window on Plugin Container (but not always).

I hope this will help you to understand the bug.

thanks for following up, i think we are getting closer to the root of the issue :) yet another ask though: could you run a http log with firefox 49.0.1 (maybe just let it sit idle in the background for 60secs or so) like requested in the bug report and attach it there...

the instructions how to do this would be at https://developer.mozilla.org/en-US/docs/Mozilla/Debugging/HTTP_logging#Logging_HTTP_activity - please let us know if anything is unclear there and we will try navigating you through it.