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!

Ce site disposera de fonctionnalités limitées pendant que nous effectuons des opérations de maintenance en vue de vous proposer un meilleur service. Si un article ne règle pas votre problème et que vous souhaitez poser une question, notre communauté d’assistance est prête à vous répondre via @FirefoxSupport sur Twitter, et /r/firefox sur Reddit.

Rechercher dans l’assistance

Évitez les escroqueries à l’assistance. Nous ne vous demanderons jamais d’appeler ou d’envoyer un SMS à un numéro de téléphone ou de partager des informations personnelles. Veuillez signaler toute activité suspecte en utilisant l’option « Signaler un abus ».

En savoir plus

Firefox says that I have a firewall that prevents me from connecting to Internet?

  • 1 réponse
  • 5 ont ce problème
  • 1 vue
  • Dernière réponse par cor-el

more options

I´ve used Firefox for a while now and I was really happy until now it just won´t work any more. When i try to connect to Internet with firefox I get a message "Connection failed" My firewall is preventing me from connecting according Firefox. But I´ve really done everything from turning my Firewall off and it still doesn´t work. I do not have any antivirus thats preventing Firefox from connecting. Internet Explorer still works perfect though.

Please, could someone help me because i don´t want to use Internet Explorer.

This happened

Every time Firefox opened

I was updating Firefox

User Agent

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; InfoPath.2; OfficeLiveConnector.1.3; OfficeLivePatch.0.0)

I´ve used Firefox for a while now and I was really happy until now it just won´t work any more. When i try to connect to Internet with firefox I get a message "Connection failed" My firewall is preventing me from connecting according Firefox. But I´ve really done everything from turning my Firewall off and it still doesn´t work. I do not have any antivirus thats preventing Firefox from connecting. Internet Explorer still works perfect though. Please, could someone help me because i don´t want to use Internet Explorer. == This happened == Every time Firefox opened == I was updating Firefox == == User Agent == Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; InfoPath.2; OfficeLiveConnector.1.3; OfficeLivePatch.0.0)

Toutes les réponses (1)

more options

In Firefox 3.6.4 and later the default connection settings have been changed to "Use the system proxy settings". See "Firefox connection settings" in Server Not Found - Troubleshoot connection problems

You can find the connection setting here: Tools > Options > Advanced : Network : Connection If you do not need to use a proxy to connect to internet then select No Proxy'


Another possible cause is security software (firewall) that blocks or restricts Firefox without informing you about that, possibly after detecting changes (update) to the Firefox program. Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox.

See Server Not Found - Troubleshoot connection problems and Configure firewalls so that Firefox can access the Internet and http://kb.mozillazine.org/Firewalls