Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Have upgrade to 5.0 and now when I load some websites I'm getting javascript application assert failure warning - what is wrong

  • 3 replies
  • 3 have this problem
  • 2 views
  • Last reply by cor-el

more options

Since upgrading to Firefox 5.0 certain websites return an error message. Javascript application is the heading and Assert failure the message. I have found on some sites that where information is being uploaded that the page stalls until the refresh button is clicked.

Since upgrading to Firefox 5.0 certain websites return an error message. Javascript application is the heading and Assert failure the message. I have found on some sites that where information is being uploaded that the page stalls until the refresh button is clicked.

Chosen solution

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

  • Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

  • Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

Read this answer in context 👍 0

All Replies (3)

more options

Chosen Solution

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

  • Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

  • Tools > Options > Privacy > Cookies: "Show Cookies"

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

more options

Thank you for your help. Clearing the offline storage(cache) solved the problem.

more options

You're welcome