Closed Bug 1308462 Opened 7 years ago Closed 7 years ago

Firefox is unable to load


(Web Compatibility :: Desktop, defect)

Firefox 50
Not set


(Not tracked)



(Reporter: JuliaC, Assigned: adamopenweb)




(Keywords: regression, Whiteboard: [sitewait])

- This is a follow up for bug 1071646

[Affected versions]:
- latest Nightly 52.0a1 (2016-10-06)
- latest Aurora 51.0a2 (2016-10-07)
- 50.0b5 (20161006105459)

[Affected platforms]:
- Windows 10 x64
- Mac OS X 10.11.6
- Ubuntu 14.04 x86

[Steps to reproduce]:
1. Launch Firefox
2. Go to

[Expected result]:
- Page successfully loads

[Actual result]:
- Page is not loaded; a version compatibility error is shown instead (see the screenshot

[Regression range]:
- Last good revision: 0a3b6e2df6567d845f31c000c68dd67816c6153d
- First bad revision: c567db06882e3a2e3396b6a16449522d149c7146
- Pushlog:
Are you sure that range is correct? There's not much in it...
Flags: needinfo?(iulia.cristescu)
(In reply to Jan de Mooij [:jandem] from comment #1)
> Are you sure that range is correct? There's not much in it...

Yes. I searched again for a regression range on Windows 10 x64, using mozilla-central repo and the results are the same.
Flags: needinfo?(iulia.cristescu)
That regression range includes a version number bump. Odds are very good they're doing crappy browser detection and don't know what to do with version 49.
Sorry, s/49/50
Component: JavaScript Engine → Desktop
Product: Core → Tech Evangelism
Version: Trunk → Firefox 50
Whiteboard: [needsdiagnosis]
Some funky version detection here:

function c() {
  if (g.detect("chrome/1")) {
    window.location = Config.URL + "/unsupported/desktopError.html"
  if ( && ! {
    window.location = Config.URL + "/unsupported/t"
  } else {
    if ( && !g.detect("chrome")) {
      window.location = Config.URL + "/unsupported/m"
    } else {
      if (g.browser.old || g.detect("msie 6") || g.detect("msie 7")) {
        window.location = Config.URL + "/unsupported/desktopError.html"
  if ( && (window.innerWidth > 650 || window.innerHeight > 650)) {
    window.location = Config.URL + "/unsupported/t"
  if (g.browser.firefox) {
    for (var h = 11; h > 4; h--) {
      if (g.detect("firefox/" + h)) {
        window.location = Config.URL + "/unsupported/desktopError.html";
So it seems they don't want to support any versions of Firefox that start with Firefox/11, Firefox/10, Firefox/9, Firefox/8, Firefox/7, Firefox/6 or Firefox/5. So that's why it's broken in 50, and was working in 49.

Seems like a bug? Not really sure what they were going for. Maybe they wanted to support Firefox 12 and up (but I don't know why decrementing h stopped at 5).

Good news is this site will continue to work again in Firefox 400!

Adam, can we get in touch with them?
Flags: needinfo?(astevenson)
Whiteboard: [needsdiagnosis] → [needscontact]
Let's try the lead developer on the project Michael Anthony on Twitter.
Assignee: nobody → astevenson
Flags: needinfo?(astevenson)
Whiteboard: [needscontact] → [sitewait]
Hey all,

Thanks for bringing this to my attention. Some old browser detection in there. We built that website 4 years ago and are quite a few layers removed from the end client -- not even sure who is hosting/controlling it now. It seems that someone has modified it a bit to force a certain dimension.

I will reach out to who I can in hopes of getting an update JS file live.
Taking this off triage radar but we should follow up for a site fix. Is it working now? (Site loads for me on Mac nightly)
Flags: needinfo?(astevenson)
This is working for me in Firefox 52 for OSX. Thanks for the help Michael!
Closed: 7 years ago
Flags: needinfo?(astevenson)
Resolution: --- → FIXED
Product: Tech Evangelism → Web Compatibility
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