If you have a problem connecting to a website, you may see error messages like '''Server Not Found'''. This article describes how to troubleshoot problems that cause this error. *For troubleshooting other error messages, see [[Error loading web sites|Error loading websites]]. __TOC__ = Check another browser = To begin, try opening a website in another browser (such as {for win}Internet Explorer{/for}{for mac}Safari{/for}{for linux}Epiphany or Chromium{/for}). * If all browsers cannot load the website, move on to the [[#w_no-browsers-can-load-websites|next section]]. * If the other browser can load the website, skip ahead to the [[#w_firefox-cannot-load-websites-but-other-browsers-can|Firefox cannot load websites but other browsers can]] section. = No browsers can load websites = If neither Firefox nor your other browser can load websites, your problem is not in Firefox, so you should seek support elsewhere{for win,mac}:{/for}{for linux}.{/for} {for win} * '''(Windows 7)''': See [http://windows.microsoft.com/en-us/windows7/Why-can-t-I-connect-to-the-Internet Why can't I connect to the Internet] at Microsoft.com. * '''(Windows Vista)''': See [http://windows.microsoft.com/en-us/windows-vista/Troubleshoot-Internet-connection-problems Troubleshoot Internet connection problems] at Microsoft.com. * '''(Windows XP)''': See [http://www.microsoft.com/windowsxp/using/networking/maintain/troubleshoot.mspx Troubleshooting network connection problems] at Microsoft.com {/for} {for mac} * See [http://docs.info.apple.com/article.html?path=Mac/10.6/en/8341.html If you can’t connect to the Internet] at Apple.com. {/for} {for win,mac}You should also check the following:{/for}{for linux}You should begin by checking the following:{/for} * Make sure you modem and/or router are both on and are not indicating errors. * If you are using a wireless connection, make sure that you are connected to the right access point. * Make sure your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is not blocking connections to the Internet. For instructions on how to configure some programs, see the [[Firewalls]] article. * If you use a proxy server, make sure that the proxy server can connect to the Internet. For instructions on configuring proxy settings in Firefox, see [[#w_firefox-connection-settings|Firefox connection settings]] below. = Firefox cannot load websites but other browsers can = If Firefox cannot load websites, but your other browser can, follow the instructions below. == Cannot load websites after updating Firefox == If you were able to load websites until you updated Firefox, your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is likely preventing Firefox from connecting to the Internet. Some Internet security programs can block Internet access even when they are in a "disabled" state. In general, you should remove Firefox from your program's list of trusted or recognized programs, then add it back. For instructions on how to configure some programs, see the [[Firewalls]] article. == Firefox connection settings == If you connect to the Internet through a proxy server that is having connection problems, you will not be able to load websites. To check your Firefox proxy settings: # [[T:optionspreferences]] # Select the {menu Advanced} panel. # Select the '''Network''' tab. # In the Connection section, click {button Settings...}. # 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{for win} (such as Internet Explorer - see [http://windows.microsoft.com/en-US/windows7/Change-proxy-server-settings-in-Internet-Explorer Microsoft's guide to proxy settings]){/for}{for mac} (such as Safari - see [http://docs.info.apple.com/article.html?path=Safari/5.0/en/9299.html Apple's guide to proxy settings]){/for}. # Close the Connection Settings window. # [[T:closeOptionsPreferences]] == DNS Prefetching == [https://developer.mozilla.org/En/Controlling_DNS_prefetching DNS Prefetching] is a technique Firefox uses to speed up loading new websites. To disable DNS Prefetching: # [[T:aboutconfig]] # [[T:contextmenu]] in the list of preferences, select {menu New}, and then select {menu Boolean}. # In the '''Enter the preference name''' window, enter {pref network.dns.disablePrefetch} and click {button OK}. # Select {pref true} when prompted to set the value and click {button OK}. == IPv6 == Firefox supports [http://en.wikipedia.org/wiki/IPv6 IPv6] by default, which may cause connection problems on certain systems. To disable IPv6 in Firefox: # [[T:aboutconfig]] # In the '''{for not fx11}Filter{/for}{for fx11}Search{/for}''' field, type {pref network.dns.disableIPv6} # In the list of preferences, double-click {pref network.dns.disableIPv6} to change its value from {pref false} to '''{pref true}'''. = Firefox cannot load certain websites = If you find that Firefox can load some websites but not others, {for win}first{/for} clear your Firefox cookies and cache: [[T:clearCookiesCache]] {for win} == Check for malware == If clearing your cookies and cache did not enable you to load the websites that did not work in Firefox, you should check your computer for [http://en.wikipedia.org/wiki/Malware malware]. Certain types of malware are known to target Firefox and can prevent it from loading various websites: * If you have an antivirus or Internet security program, update its detections database and do a full scan of your system. * If you still have problems, see [[Is my Firefox problem a result of malware#w_how-do-i-get-rid-of-malware|How do I get rid of malware?]]. {/for} <!-- MZ credit --> <br/> <br/> '''''Based on information from [http://kb.mozillazine.org/Error_loading_websites Error loading websites (mozillaZine KB)]''''' [[Template:ShareArticle|link=http://mzl.la/Nn0kzJ]]

If you have a problem connecting to a website, you may see error messages like Server Not Found. This article describes how to troubleshoot problems that cause this error.

• For troubleshooting other error messages, see Error loading websites.

Check another browser

To begin, try opening a website in another browser (such as Internet ExplorerSafariEpiphany or Chromium).

• If all browsers cannot load the website, move on to the next section.
• If the other browser can load the website, skip ahead to the Firefox cannot load websites but other browsers can section.

No browsers can load websites

If neither Firefox nor your other browser can load websites, your problem is not in Firefox, so you should seek support elsewhere:.

You should also check the following:You should begin by checking the following:

• Make sure you modem and/or router are both on and are not indicating errors.
• If you are using a wireless connection, make sure that you are connected to the right access point.
• Make sure your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is not blocking connections to the Internet. For instructions on how to configure some programs, see the Konfigurer din firewall, så Firefox kan få adgang til Internettet article.
• If you use a proxy server, make sure that the proxy server can connect to the Internet. For instructions on configuring proxy settings in Firefox, see Firefox connection settings below.

Firefox cannot load websites but other browsers can

If Firefox cannot load websites, but your other browser can, follow the instructions below.

Cannot load websites after updating Firefox

If you were able to load websites until you updated Firefox, your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) is likely preventing Firefox from connecting to the Internet. Some Internet security programs can block Internet access even when they are in a "disabled" state.

In general, you should remove Firefox from your program's list of trusted or recognized programs, then add it back. For instructions on how to configure some programs, see the Konfigurer din firewall, så Firefox kan få adgang til Internettet article.

Firefox connection settings

If you connect to the Internet through a proxy server that is having connection problems, you will not be able to load websites. To check your Firefox proxy settings:

1. Klik på menuen Firefox i menulinjen øverst i vinduet, og klik så på Indstillinger.Klik på menuknappen , og klik så på Indstillinger.
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. Luk fanebladet Indstillinger. Ændringer gemmes automatisk.

DNS Prefetching

DNS Prefetching is a technique Firefox uses to speed up loading new websites. To disable DNS Prefetching:

1. Skriv about:config i adressefeltet, og tryk på tasten EnterRetur.
   En advarselsside vises måske. Klik på knappen Accepter risikoen og fortsæt for at gå til siden about:config.
2. HøjreklikHold tasten Ctrl nede mens du klikker in the list of preferences, select New, and then select Boolean.
3. In the Enter the preference name window, enter network.dns.disablePrefetch and click OK.
4. Select true when prompted to set the value and click OK.

IPv6

Firefox supports IPv6 by default, which may cause connection problems on certain systems. To disable IPv6 in Firefox:

1. Skriv about:config i adressefeltet, og tryk på tasten EnterRetur.
   En advarselsside vises måske. Klik på knappen Accepter risikoen og fortsæt for at gå til siden about:config.
2. In the FilterSearch field, type network.dns.disableIPv6
3. In the list of preferences, double-click network.dns.disableIPv6 to change its value from false to true.

Firefox cannot load certain websites

If you find that Firefox can load some websites but not others, first clear your Firefox cookies and cache:

1. Klik på menuknappen Billedet "fx57menu" findes ikke. for at åbne menuen.
2. Klik på Historik, og klik så på Ryd seneste historik…
3. Klik på rullemenuen ud for Fjern, og vælg Hele min historik.
4. Sæt flueben ud for både Cookies og Cache under Historik. Sørg for, at andre elementer, du vil beholde, ikke er valgt.
5. Klik på knappen OKRyd nu.

Based on information from Error loading websites (mozillaZine KB)