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Made several attempts to download and each time I get message saying the URL address is not valid and cannot be loaded.

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  • Last reply by cor-el

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Firefox worked on my desktop for years. About 3 weeks ago it stopped and every time I clicked on the icon I got a message saying: "The address isnt valid. URL not valid and cannot be loaded." I unintsalled firefox and then tried 3 websites (2 from suggestions to other people's questions from mozilla support page) to re-download it and got the same error message each time.

I have Windows 7 Home Premium. Any help is appreciated. Thanks

Firefox worked on my desktop for years. About 3 weeks ago it stopped and every time I clicked on the icon I got a message saying: "The address isnt valid. URL not valid and cannot be loaded." I unintsalled firefox and then tried 3 websites (2 from suggestions to other people's questions from mozilla support page) to re-download it and got the same error message each time. I have Windows 7 Home Premium. Any help is appreciated. Thanks

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You can check the target line in the Firefox desktop shortcut (right-click: Properties) to make sure that nothing is appended after the path to the Firefox program.


You can check for problems with preferences.

Delete possible user.js and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release.

You can use this button to go to the current Firefox profile folder:


Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

  • Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
  • Do NOT click the Reset button on the Safe Mode start window