Fix Unresponsive Script Warning

Notice: This article is no longer accurate, please see Warning Unresponsive Script for more updated information.

There are times depending on what is running in the background and other Internet activity that Firefox (or Thunderbird) may get bogged down and a JavaScript may take a little longer than normal to complete. Users will get a warning similar to the one below advising that the script is unresponsive.  The reason for this is because the application thinks the script is running wild and never going to finish processing thus causing the application to freeze and/or crash. This is very similar to Windows Task Manager warning you that an application is not responding, but the application is just a bit bogged down (which commonly happens with JavaScript) and needs more time to finish what it is doing.

The ‘fix’ for this is fairly simple, just increase the amount of time before a script is considered ‘unresponsive’. This can be done in both Firefox and Thunderbird via about:config (Firefox) and the Config Editor… (Thunderbird):


  1. In a new tab type about:config in the address bar and press enter
  2. In the about:config manager type dom.max_script_run_time in the Filter field
  3. Double click the entry and in the in the pop-up box type 20 and press enter
  4. Close the tab


  1. Go to Tools >> Options…
  2. Click on the Advanced tab on top
  3. At the bottom of the window is a section Advanced Configuration
  4. Click on the Config Editor… button at the lower right
  5. In the Config Editor… type dom.max_script_run_time in the Filter field
  6. Double click the entry and in the in the pop-up box type 20 and press enter
  7. Close the window

Source: Itchy Hands

54 Comments on Fix Unresponsive Script Warning

  1. Thanks a ton, this has been nagging me. I just fixed the timer so I haven’t had any more problems yet. I’m sure this is the cure!

  2. Judith Little | August 26, 2010 at 12:26 PM |

    OMG! I got control over MY computer again! Thank you, thank you, thank you!!!! You were the only one who said to type about:config in the address bar IN A NEW TAB. It sure as @#$% didn’t work in the original one. Anyhow, I then got the warning about the warranty and i promised to be careful. Then I didn’t have to type in the filter field….a complete list of all the which-a-majigs ( I am not computer literate) came up. I just scrolled down to the one you identified, highlighted and double clicked it, then changed the 10 to 20. Guys have got to realize that their instructions are like recipes….leave the baking powder out of the cake and you get a brick!

  3. Thanks a bunch! I have uninstalled/reinstalled FF, plugins, everything trying to kill this problem. Why did it crop up all the sudden? This info needs to be more widely disseminated.

  4. Tremendous! It worked, awsome…goodbye Mr Freeze!!

  5. oooooh! thank you! thank you!…very clear instructions

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  7. Thank you for addressing the symptom and reducing the number of times the window pops up.

    I have a bigger question, though: If it ‘s Javascript that’s causing the issue, is there anything that can be done to our Javascript that will cause it to execute the scripts more effectively and not appear to hang as often?

    I’m running FF4 and seem to have this issue much more often than with FF3. I don’t know if it’s a compatibility issue with JS or if the old settings just don’t work the same with FF4, but it does happen a lot.

  8. Chris Woollon | June 11, 2011 at 10:46 AM |

    Hi, straight forward, easy to do, done! Simple! Goodbye “unresponsive scripts”! Thanks a bunch for that, it’s nice to use something that actually works!

  9. great work , god bless and thanks for your help.

  10. Thanks a lot, my linux always crash as often in this issue. you save lot my time…

  11. Changed dom.max to 20 but did not work. Browser still freezes and get this pop up:

    Warning: Unresponsive Script
    A script on this page may be busy, or it may have stopped responding. You can stop the script now, or you can continue to see if the script will complete.
    Script: chrome://vidbar/content/downloader.js:120

    Noticed this problem occurred after installing Firefox 3.6.23 and usually on sites having flash properties like the New Yahoo! mail and Facebook.

    • I just started getting this error a week or so ago. Tried the above fix & it didn’t help me, either. 🙁

  12. I started getting these crashes about a month ago. I tried the above things and they did not help. I upgraded my firefox as (someone said the new ones has less issues)and it is still doing it. I disabled my add ons (I only had 2) and it is still doing it. I get the unresponsive script errors. They point to diff things each time. I get freezes regularly and have to use the task manager to close the program and re-open it. I also get these errors and freezes with the new thunderbird.

    The places it does it the most is facebook and pages with flash and java

    • ThaPeastenator | December 5, 2011 at 7:03 PM |

      I’m also having the same problem. It’s really pissing me off, it started happening to me a month ago and for a while it stopped, but then it started again. I think it’s about time I make the switch from Fagfox to a better, more reliable browser.

  13. Cool gents,…muchos gracias !!!

  14. its not working for mac 🙁

  15. Did it. It does not work for me on my PC.

  16. Rob Roper | March 5, 2012 at 1:26 PM |

    I’d like to try your fix but under “Tools” there is no “Options”. I have Thunderbird 3.1.11 for the Mac. (I haven’t upgraded past that because it seems that every so-called “upgrade” is slower and has more bugs.) Where would this be located on my version? I don’t see “Options” under any of the menu selections.

  17. I could hug you! This problem was soooooooooo annoying. It stopped everything from working for minutes at a time. Thanks for doing a good job explaining.

  18. Very informative blog post.Really thanks! Really Great.

  19. I tried it but it does not work, i get this unresponsive script the most on facebook, all other websites has constant freezing. Is there another solution as this is driving me crazy. Also does anyone have an answer to a jumping cursor. I have installed Touch Freeze but still this does not work. I am using Mozilla. Any answers, PLEASE!!!!!

  20. On GNU/Linux Debian Squeeze, using FF (called Iceweasel) this has become such an issue that even with NoScript and trying the above fixes, the entire browser just hangs and becomes unresponsive. This esp the case when browsing Google’s searches (images, etc.).

    Our developers at Mozilla really should bug trace this problem as it is making me inclined towards using an alternative just that I can get some work done without hanging for ages.

  21. Mine was set at 1800, so I certainly wasn’t going to change it back to 20. So I am wondering two things: 1. Why was mine set so high? I didn’t do that deliberately, anyway, and 2. What program is running the script? Is this part of Firefox, or some firefox addin?

  22. Can’t believe this is *still* a problem. Just started for me about 2 weeks ago and I haven’t been able to clear it up yet. Upgraded to latest Thunderbird (v14.0), updated all the plugins, disabled all the plugins. It only happens on my inbox for one of the several accounts defined. All of the other inbox folders and personal folders are ok. Removed inbox.msf to force a rebuild – no change. Tried compacting inbox – no change. Tried changing the above dom.max_script_run_time value from 10 to 20 – no change. Not sure if this is caused by a microsoft patch to Windows XP, or a mal-formed email message in the inbox, or what… I’m slowly copying out or removing email messages from the inbox, but its *very* painful as every copy or deletion takes about 5 minutes *each*. I don’t know why the Thunderbird crew can’t fix this after all this time… Sigh 🙁

  23. I too have this unresponsive script thing. I too have changed my config to 20 without any help. I have firefox, Vista and mostly happens in facebook but has happened on other sites. When is Modzilla ever gonna fix this? So so annoying. I can’t do the things I want to do so why have it?

    • This is not something that Mozilla can fix. The problem is the websites, especially Facebook that run multiple scripts in the background that is bogging down the browsers. This also seems to be more of an issue with Windows Vista as I don’t see this nearly as often in Windows 7 systems as I have in Vista.

      • Actually it IS Mozilla’s problem. OF COURSE sites are buggy, but at least Mozilla could offer a solution to ignore it. So there should be an option for stopping them all automatically, for example after some time. Now there’s this option “Don’t show this again” but it doesn’t help much. (Actually, it could help, but I can’t just see the difference, because I use that option)

        • First of all, thank you that this page is here…. this has been driving me crazy for over a year…. I thought it was my computer cuz I’ve got it behind so many safeguards.

          Second, I agree with the above post: Why does the “don’t show this again” button not seem to help at all? I don’t want to change the length of time it waits for a script, I want it to just quit trying to run them after I’ve told it not to.

          btw, not sure if anyone else has had this, but it only happens to me when I’ve left my computer running with a certain couple of sites open for more than 15 minutes or so without accessing those sites. It never happens when I’m actively using those pages.

  24. Had to take a minute to say thanks for your very clear and concise directions on how to deal with the unresponsive script problem. it was driving me crazy and worst of all I thought I had a virus – I still might but at least the script problem is solved. Thanks again.

  25. Had to take a minute to say thanks for your very clear and concise directions on how to deal with the unresponsive script problem. it was driving me crazy and worst of all I thought I had a virus – I still might but at least the script problem is solved. Thanks again.

  26. Good job Buddie!!!! Very straight forward and informative. This is the first time i actually want to donate!!! thanks a ton , i been going crazy!!

  27. is there anyway to get a list of the scipts runing in the background anywhere? I probably need to finad and delete some of the more offending scripts…

  28. Thx a lot I was even think was a virus…Thx a lot!

  29. Have updated the dom.max_script_run_time to 20 and was still slow. Now I am trying to set it to 30 to see if I see some improvement.
    Does anyone know of a permanent fix?

    • Doesn’t work,i even tried 9999, just makes it take longer. Set it to 1. You still get the message box but at least it’s instant and you can stop the script right away.

  30. out of desperation, I have installed NOSCRIPT extention to FIREFOX (FREEWARE).

    no script has full blacklisiting capabilities for all background scripts. althought it is initially a pain to examin each site you visit (all java scripts are listed for you review and either permenant or temp. approval)

    it is a real eye opener to see haw many unneccesary scripts are loaded on various sites…

  31. I strongly recommend NO SCRIPT for firefox, it immediately highlights the scripts that are active on a page,and give some very granular opportunities to block selected scripts, or all of them, etc.

    FIREFOX should consider buying this company immediately, and promote itself as the browser of choice for fighting these rogue websites…

  32. I hope the link I just mentioned with be easy to use. The firefox is already a great effort and yet they are in action. Try safe surfing and alongwith the “YesScript” you may feel relax.

    Be in peace.

  33. Indonesian :) | July 13, 2013 at 3:52 AM |

    it works!

  34. Thanks for this clear article ,
    I am facing little different problem , my client has the same issue “unresponsive script” , although its working fine on my end on all OS and browsers.
    How do I can over come this issue as I am unable to reproduced the same .
    Thanks in advance !

  35. Hi Pankaj,

    Since I used :


    I almost forgotten that I have had this problem. I looks like your customer’s OS need to be updated and or re-installed (you did not mentioned which Window’ version he/she is using) and also it depends of the User level i.e. Simple user to Power user. And there is max. chances of having a bug or virus. For your information my system has updated ver. of Norton. I am in love with Norton since DOS ages.

    Try to use something to deep scan the system. Because the solution provided by the FireFox is (to me) a complete solution.

    Leaving multiple pages open and unattended also creates the problem.

    I’ll do my best to recheck and find something according to your need. But its not a promise of short time as i find something I’ll post immediately.

    for the meantime Wish you luck,

    • Thanks for showing your keen concern about this issue , means while I have come around some solution and waiting for client’s confirmation . The issue is like one of the ajax call has not find correct URL and fortunately that issue regenerate over my end by reducing max limit .

      Once again thanks for your help.

  36. Here’s what I tried: I cleared all cookies with the word “yahoo” in them. Didn’t work. I cleared cookies from the server that kept giving me the “unresponsive script” error, and that didn’t work. Finally, this worked: 1. shut down all yahoo tabs and windows — yahoo mail, yahoo answers, etc.. 2. Clear all cookies. 3. Shut down Firefox. 4. Restart Firefox and log back into yahoo mail. (If you don’t have to log back on to yahoo, then cookies were not cleared.) My error involved the script “ebExpBanner.js” so if a different script is your problem, this fix might not work. I started to get this error after Firefox crashed once. Still, I’m looking into NoScript.

  37. I’ve tried your “fix” – it doesn’t work on my Mac ( running system 10.9). I’ve been through the Mozilla help pages and tried various solutions detailed there. I’ve sent about a dozen questions to the Mozilla help forums. Many people have been kind enough to make suggestions which I’ve followed. By now practically all the fixes people suggest to me are ones I’ve already tried.

    I used Firefox up to version 3.5 and it worked well. But ever since, Firefox has frozen as soon as I’ve opened a webpage other than Google. Firefox even froze once in a Mozilla’s help page ! I’m now using (or trying to use) version 25.

    Thanks for suggesting a “fix”. Not your fault if it didn’t do the trick. Besides, adjustments shouldn’t be necessary. Other browsers work well, without needing any adjustments.

    Firefox is, quite simply, a bad browser.

  38. Is there a way to tell from the error message which TAB or URL contains the failing script?

  39. This shit has been going on for half a decade, HALF A FUCKING DECADE, and yet there is still no help beyond “give the unresponsive script more time”, which only makes it not respond for longer. Firefox, just stop unresponsive scripts automatically!

  40. Thnks i had the same issue too

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