On some pages I get the "Script not responding" error with an option to stop it and a checkbox to never ask again.

Later I get the same question again, with that pointless checkbox.

How do I make Firefox always stop a script when it's not responding?


You have to adjust dom.max_script_run_time in about:config to higher value.

As noted previously, this timeout also applies to add-ons using Javascript, as such it will be reached easily on slow computers using AdBlock, or even AJAX-rich websites like Google Docs etc.

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  • Also dom.max_chrome_script_run_time. – harrymc Jan 31 '12 at 10:09
  • Ur right, your timeout applies to extensions... – ZaB Jan 31 '12 at 16:02
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    All this does is allow the scripts to run longer, effectively like always hitting the "Continue" button the first time. The OP (and me) wants the opposite: to always hit the "Stop Script" button the first time. – David Nelson Mar 9 '12 at 0:33
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    This is a non-answer. Three different websites I've been to looking for an answer to this, and each time the most "helpful" response is to avoid problematic scripts or lengthen the time. Why have a "stop script" button when it does nothing (and hasn't ever...) – Glenn Feb 11 '13 at 2:02
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    This don't answer the question, he is asking about how to make firefox auto stop the script, and didn't ask about how to allow it to run for more time – Ahm3d Said Oct 17 '14 at 22:47

This sounds like a job for YesScript!

This add-on will let you to create a blacklist of sites that are not allowed to run java script. Let me know how it works out for you.

Resources (please refer to this link for more solutions): Warning: Unresponsive Script

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    NoScript is much safer. – harrymc Jan 31 '12 at 16:20
  • @harrymc Right you are. I've never read or heard about NoScript up until this moment. From the research that I've done, YesScript is NoScript's Antagonist... quite a good way of putting it in this article. – Rob Feb 1 '12 at 2:09
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    @harrymc NoScript breaks every website you visit. It's safe like never leaving your house is safe. – endolith Aug 11 '15 at 20:28
  • NoScript is tedious how you have to fine tune each site. There must be a better way of doing things. – James P. Jul 20 '19 at 22:59

There is a big difference between a script going into a loop or waiting upon a server on the Web. Normally it is the second case which causes "Script not responding" errors.

Firefox has got no way of knowing the difference between a Web server not responding or just being slow. So it has a couple of dumb guillotine-type cut-off mechanisms like dom.max_script_run_time and dom.max_chrome_script_run_time, which specify how long it is willing to wait before canceling the script and any connection it might be waiting upon at the moment.

These sort of mechanisms are very dangerous to use. For example, while buying an item on the Web, the online payment site may be slow to react, so Firefox will just cancel the script and connection with unknown results as regarding your bank account.

What I am trying to say is that getting rid of these "Script not responding" errors may be worse than the errors themselves. You might be better off using an extension like NoScript to disallow all javascript on all websites you visit except for the ones you trust (or at least disallow third-party javascript). This is actually a defense mechanism that you and everyone should be using against drive-by-browser viruses.

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With the plugin NoScript you are able to stop/block any script on a web page one by one.

If you know which script isn't responding you will be able to add it on the NoScript black list and it will never disturb you again.

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Do you have any add-on's such as Noscript, Adblock, Ghostery and TACO?

If yes, then there is conflicts with these add-on's.

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  • Certainly not with NoScript. – harrymc Jan 31 '12 at 16:21

Set dom.always_stop_slow_scripts to true.

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