cancel
Showing results for 
Search instead for 
Did you mean: 

Firefox hangs when scripts run, works fine with Javascript off

Highlighted
New User

Firefox hangs when scripts run, works fine with Javascript off

Turning Javascript off makes firefox work like normal. Other browsers have no issue. This started acting up on me about 4-5 days ago. Quite annoying to not be able to run firefox with javascript on. Is there a way to reinstall javascript?

I have tried safe mode, resetting firefox, reinstalling firefox, disabling addons, changing profiles, it really comes down to javascript being turned off fixes it for me. So despite being fairly computer savvy, I have no idea what is causing this. I ran Microsoft security essentials, a few malware/spyware utilities, checked hijackthis. I cannot find the issue. Firefox likely submitted 50+ crash reports.

bp-2be6c833-69ea-45e3-bdb9-a77422130617

is one crash report, I tried to get one of the earlier ones to see if that would help, not sure if this one will, I have plenty of them. But I'll load a page or a couple of pages and firefox will hang, it won't crash outright, but I end up using Task manager to close it.

Tags (2)
9 REPLIES
SUMO Contributor

Re: Firefox hangs when scripts run, works fine with Javascript off

Thank you for the crash link. When I scroll down and look at related bugs, all of them seem to mention Flash.

This is some standard guidance that addresses the most common issues with the Flash player. I'm sure you've seen some of it before, but just in case:

(1) Make sure all recorders/downloaders that interact with Flash media are as up-to-date as possible, or disable them.

(2) Disable hardware graphics acceleration in Firefox and in Flash

(A) In Firefox, un-check the box here and restart:

orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"

(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

(3) Disable protected mode (Windows Vista/7/8)

See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

SUMO Contributor

Re: Firefox hangs when scripts run, works fine with Javascript off

JavaScript is part of Firefox and there's no separate installation.

Are you getting the slow script dialog or does everything just come to a halt without any messages?

There is a JavaScript compiler in Firefox that is optional and can be disabled. But then Firefox's Safe Mode would have worked normally, so if that didn't help, it's probably not relevant.


Could you try disabling the JavaScript debugger? I think it was just turned on in Firefox 21. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the filter box, type or paste devt and pause while the list is filtered

(3) Double-click devtools.debugger.enabled to toggle its value from true to false. It should turn bold. (I don't know whether this takes effect immediately or after a restart.)


There are add-ons to manage which sites can use JavaScript, which might be helpful as a short term coping strategy or a lifestyle (I'm in the second category). In particular, you could consider using the NoScript extension. More information: http://noscript.net/

New User

Re: Firefox hangs when scripts run, works fine with Javascript off

I apologize, I'm a knucklehead, I thought I tried the hardware acceleration a few times, but it seems I didn't try properly or something as that seemed to fix it. The good news is my hair should grow back from all the ones I pulled out trying to figure this out over the past few days. Thanks for your calm, patient, and understanding responses.

SUMO Contributor

Re: Firefox hangs when scripts run, works fine with Javascript off

If that takes care of all the problems, that would be amazing. I'll keep my fingers crossed for you.

New User

Re: Firefox hangs when scripts run, works fine with Javascript off

I have the same problem, and have tried your suggestions: - disabling hardware graphics acceleration in Firefox has no effect - disabling javascript as indicated (in about:config) : no more freeze. - enabling javascript and disabling devtools.debugger : still freeze, however in some pages the freeze is less important (shoter).

The page i used for tests : www.colissimo.fr (on this page disabling debugger has no effect)

Disabling javascript is not a solution at all, as in that case for example i can't access to outlook (hotmail) !.....

Note : i'm with Firefox 25.0 on Win7 64bits

Is there any other solution ???

SUMO Contributor

Re: Firefox hangs when scripts run, works fine with Javascript off

Hi StephAub, is the problem on that specific page (http://www.colissimo.fr/)? I don't see anything special about that page. I assume you have tried the usual for when a particular page is not behaving well:

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

orange Firefox button (or Tools menu) > Options > Advanced

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

  • right-click and choose View Page Info > Security > "View Cookies"
  • Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page.


As a test, could you disable the Flash Player plugin and try the problem pages again? On the Add-ons page (Ctrl+Shift+a) set Shockwave Flash to "Never Activate".

New User

Re: Firefox hangs when scripts run, works fine with Javascript off

Hi jsher ! thanks a lot for quick and efficient answer. I have good news : - when deactivating shockwave add-on as you indicated (i have 11.9.900.117) i don't have the freeze anymore on this page ! - if i re-activate shockwave add-on: problem is back. - i also tried to refresh page as you indicated (with shockwave activated) : same freeze.

3 additional comments: - i have this freeze issue on different pages (not only the one indicated). So i will check with other pages now with shockwave deactivated - this freeze duration (on this page) is 5 minutes, but within these 5 minutes i have from time to time "the hand" again (but it is so short that i can't do any other action on firefox until freeze end, i.e. after 5 minutes). - i had the same pb with previous release of shockwave add-on.

SUMO Contributor

Re: Firefox hangs when scripts run, works fine with Javascript off

Hi StephAub, were you able to disable the Protected Mode of the Flash Player plugin earlier? Although in theory this feature provides valuable security benefit, it remains a bit buggy and simply doesn't work well on all systems.

See this support article from Adobe under the heading "Last Resort": Adobe Forums: How do I troubleshoot Flash Player's protected mode for Firefox?

New User

Re: Firefox hangs when scripts run, works fine with Javascript off

Hi Jscher, no i hadn't been able to disable protected mode of the flash player plugin - i didn't find how to do that.

But it seems i have finally solved my pb with complete uninstall of flash (by uninstall of Adobe products) then re-install . I have now shockwave flash plugin 11.9 r900 - so slightly different than the one i had before - and i don't have freeze any more .... at the moment.

so i cross fingers.... in any cases, thanks for your help.