Firefox ESR 52.x won't connect to specific site
I'm having trouble connecting to one specific site, http://bruursmoergestel.nl/, with any version of Firefox ESR 52.x for Windows. Firefox ESR tries to connect (by showing the rotating circle and 'Connecting' in the tab and 'Waiting for bruursmoergestel.nl' in the status bar) but after a couple of minutes the connecting stops, and nothing visually has changed. Internet Explorer, Chrome and 'regular' Firefox are loading the site instantaneously. I experienced this issue at work (I'm the IT admin for Firefox in our organization), and I ruled out any OS version, add-on, network or proxy influences by trying at different physical locations (work, home) and computers and clean installs (including clean user profiles), running in safe mode and trying different language versions (en-US and nl) of Firefox ESR (52.0, 52.2 and 52.4.1). The issue seems only to occur in Firefox ESR 52.x, and not in Firefox 50.0.2, 55.0.3 and 56.0.1. The site HTML code looks pretty straight forward to me, and since it loads in 'regular' Firefox I'm expecting that the code is not the cause of the issue. It looks like a bug in Firefox 52.x. Can you help me resolve this issue?
Krejt Përgjigjet (7)
Hello,
Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).
If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:
- Click the menu button
, click Help 
and select Restart with Add-ons Disabled.
If Firefox is not running, you can start Firefox in Safe Mode as follows:
- On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
- On Mac: Hold the option key while starting Firefox.
- On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
(you may need to specify the Firefox installation path e.g. /usr/lib/firefox)
When the Firefox Safe Mode window appears, select "Start in Safe Mode".
If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.
To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.
When you figure out what's causing your issues, please let us know. It might help others with the same problem.
Thanks for your post. Please read my question carefully, I already tried a lot of things, including Safe Mode. So that is not the solution. The issue is easily reproducible for anyone who installs Firefox ESR 52.x and tries to visit http://bruursmoergestel.nl.
Ndryshuar nga mchuijgen
My apologies, has the website worked for you in previous versions of ESR?
Thanks for your suggestion. My organization did not use the ESR channel before ESR 52.0 (because of the use of NPAPI plugins like Java and Silverlight). But I just downloaded ESR 45.9.0 from the Mozilla FTP site and installed it and it does not have the issue: http://bruursmoergestel loads as expected. Seems to be narrowed down to ESR 52.0 to ESR 52.4.1 so far. I suspect it's a bug, can it be reported anywhere?
Ndryshuar nga mchuijgen
Yes it can be at https://bugzilla.mozilla.org/ or if you want, I can file a bug for you.
That is weird. I see the same problem with Firefox 52. This even happens if I spoof the user agent in the current Firefox 56 release to be Firefox 52. This only happens when the user agent is set to Firefox 52, Firefox 51 and Firefox 53 work.
If I spoof the user agent in Firefox 52.4.0 to be a Firefox 53 version then this also works and the page loads instantly.
You would have to contact the website and ask thgem to look into this issue.
Thanks for your analysis, cor-el. I will contact the website. Really strange, why would someone block a specific user agent version... I'll keep the problem open until I know for sure.