This article contains information on diagnosing and fixing error messages that display when you try to view websites in Firefox.

Índice de contenidos

• Connection errors
• Errors loading secure sites
• Interrupted or reset connection
• Proxy errors
• Malicious website errors
• Other error messages
• Offline mode
• The page isn't redirecting properly
• File not found
• Content Encoding Error
• This address is restricted
• Other issues

Connection errors

Error messages that indicate connection problems:

• Unable to connect
• Server not found

If you experience one of these errors intermittently, check your Internet connection. If you connect wirelessly, make sure you are connected to the nearest access point and that the signal is strong.

If you experience one of these errors on all websites, see the following articles:

• Firefox cannot load websites but other programs can - if you can view websites in browsers other than Firefox.
• No programs can load websites - if you can't view websites in any browser.
• Cannot connect after upgrading Firefox - if you experience connection problems after updating Firefox.

Errors loading secure sites

If you experience an error accessing a website over a secure (HTTPS) connection, see the articles below that correspond to the error message you see:

• Secure Connection Failed
• Error code 500 accessing secure sites
• Could not initialize the browser security component

Interrupted or reset connection

The following error can occur if the website you're visiting is experiecing problems:

• The connection was interrupted
• The connection was reset
• The connection has timed out

If you can visit the website in other browsers but not in Firefox:

Proxy errors

Error messages that indicate proxy problems:

• The proxy server is refusing connections
• Unable to find the proxy server

This error indicates that Firefox is trying to access the Internet through a proxy server. To check your proxy settings:

1. At the top of the Firefox windowOn the menu bar, click on the ToolsFirefoxEdit menu, and select Options...Preferences....
2. Select the Advanced panel.
3. Select the Network tab.
4. In the Connection section, click Settings....
5. Change your proxy settings:
   • If you don't connect to the Internet through a proxy (or don't know whether you connect through a proxy), select No Proxy.
   • If you connect to the Internet through a proxy, compare Firefox's settings to another browser's (Such as Internet Explorer. See Microsoft's guide to proxy settings)(Such as Safari. See Apple's guide to proxy settings).
6. Close the Connection Settings window.
7. Click OK to close the Options windowClick Close to close the Preferences windowClose the Preferences window

Malicious website errors

If you receive one of the following errors, Firefox has blocked access to the website you're visiting to protect you from malware or web forgery (phishing).

• Suspected Attack Site!
• Suspected Web Forgery!

For more information, see Phishing and Malware Protection (Mozilla.com).

Other error messages

Offline mode

Your operating system indicates to Firefox whether it is connected to the Internet. If it reports that it is not connected, Firefox will go into offline mode. If you are connected:

• On the menu bar, click File and select Work Offline.

The page isn't redirecting properly

This problem can be caused by problems with cookies:

• See Websites say cookies are blocked.

File not found

If you experience this error when trying to access a local file (with a file:// URL), the path you are trying to access is either incorrect or inaccessible - verify the path.

If you experience this error trying to access a website, see:

• Troubleshooting extensions and themes
• Is my Firefox problem a result of malware

Content Encoding Error

The following error messages indicate a content encoding problem:

• Content Encoding Error
• The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression

Several problems can result in a content encoding error message. To dignose and fix:

1. Check the settings of any Internet security applications you use (including firewalls, anti-virus or anti-spyware programs, and privacy protection programs). You should try to remove any permissions those applications have for Firefox, and then add them again. For program-specific instructions for a number of applications, see Firewalls.
2. Follow the Standard troubleshooting steps.

This address is restricted

This error occurs when you are attempting to connect to a web server on a port that is reserved for another application.

If the web address (URL) you are trying to visit contains a colon followed by a number (e.g. http://webserver.tld:23), try removing that portion (e.g. http://webserver.tld) or replacing it with :80 (e.g. http://webserver.tld:80)

If specifying a different port does not work, you may have been given an incorrect web address.

Other issues

• Warning Unresponsive script
• The web page just doesn't look right

• Cannot log in to websites. You may receive an error similar to We were unable to process your login request or An unspecified error has occurred when you attempt to sign into websites with your username and password, or the login may simply fail.

Based on information from Error loading websites (mozillaZine KB)