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This article describes the reasons for this error message and covers possible solutions and workarounds.

Firefox may give you a "Warning: Unresponsive script" prompt that says "''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.''" This article describes why this could happen and possible solutions and workarounds. This error is telling you that Firefox thinks that a [[JavaScript settings and preferences for interactive web pages#w_what-is-javascript|script]] may be running out of control and would make Firefox hang if nothing is done. The script could be something on a web page you're accessing, in an extension you installed, or even Firefox itself. __TOC__ = Letting the script run longer = If you find that pressing the {button Continue} button brings up the same dialog again, letting the script run longer won't help you; it will just make Firefox hang for longer. However, if you can use Firefox normally after pressing {button Continue}, then the script may just needs extra time to complete. To tell Firefox to let the script run longer: {for not fx71} # [[T:aboutconfig]] # In the about:config page, search for the preference {pref dom.max_script_run_time}, and double-click on it. # In the '''Enter integer value''' prompt, type {pref 20}. # Press {button OK}. {/for} {for fx71} # [[T:aboutconfig]] # In the about:config page, search for the preference {pref dom.max_script_run_time}. # Click the ''Edit'' [[Image:Fx71aboutconfig-EditButton]] button and enter {pref 20}. # Press the checkmark [[Image:Fx71aboutconfig-Checkmark]] button to save the preference. {/for} With scripts now allowed to run for longer times, you may no longer receive the prompt. If you still receive the prompt (or if you want to see it again), you should set that preference back to the default value. # [[T:aboutconfig]] # In the about:config page, search for the preference {pref dom.max_script_run_time}. # {for not fx71}{for win,linux}Right-click{/for}{for mac}Hold down the {key Ctrl} key while you click{/for} on it and choose {menu Reset}{/for}{for fx71}Click the ''Reset'' [[Image:Fx71aboutconfig-ResetButton]] button{/for}. = Error happens when accessing certain websites = If the error happens only on a specific website, you can block scripts from running on that website. Many sites still function even if scripting is disabled. # Install the [https://addons.mozilla.org/firefox/addon/javascript-toggler JavaScript Toggle On and Off] extension. # [[T:Open Add-ons|type=Extensions]] # Find the JavaScript Toggle On and Off entry and click the {for win}{button Options}{/for}{for mac,linux}{button Preferences}{/for} button. #Scroll down to the '''Black-list''' text box and enter the URL of the site that's giving you problems. # Click {button Save}. The domain name of the site will be added to the list. Now that the problematic site has been blocked from running scripts, it will no longer cause unresponsive script warnings. [[T:addonsupport]] = Other causes = An add-on could be causing the problem. See [[Troubleshooting extensions and themes]]. <!-- MZ credit --> <br/> <br/> '''''Based on information from [http://kb.mozillazine.org/Unresponsive_Script_Warning Unresponsive Script Warning (mozillaZine KB)]'''''