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

Error message browser sent invalid command

  • 1 reply
  • 1 has this problem
  • 8 views
  • Last reply by cor-el

more options

After clicking on a link,, the following error message appears. It happens with various links and follows an automatic upgrade to FF 18.0.

400 Bad request Your browser sent an invalid request.

After clicking on a link,, the following error message appears. It happens with various links and follows an automatic upgrade to FF 18.0. 400 Bad request Your browser sent an invalid request.

All Replies (1)

more options

This error can be caused by corrupted cookies.

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

"Clear the Cache":

  • Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

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