Hello,

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information.
Note: This will cause you to lose any Extensions and some Preferences.

• Open websites will not be saved in Firefox versions lower than 25.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

Thank you.

Is http://www.example.com/ the real page? What is the real page? Do not include any personal information in the reply.

It could that you have the wrong or mistyped the address. It could be that the page is off line or shut down or a dozen other things. It could be that you or your service is block from that page. We can't help much without knowing the real web address and looking for ourselves.

Hello

Thanks for your speedy reply but unfortunately this did not work. Any other suggestions or ideas as to why this is happening?

Thanks!

Hi fredmcd-hotmail

It's not that I'm typing anything in wrong, it's when I first open Firefox or a new tab. Instead of displaying the firefox page showing my recently viewed websites it's just an invalid URL. Why would I be blocked from this page?

Thanks

Create a new profile as a test to check if your current profile is causing the problems. See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

Profile Backup and Restore

• http://kb.mozillazine.org/Profile_backup
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Does this only happen when you start Firefox?

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.

Your new tab setting should have been "reset" back to the 9-thumbnail display when you did the reset, but it is possible for an extension (or external software) to override it. An extension should be visible from inside Firefox; the mischief performed by external programs usually involves creating a user.js file.

Try disabling ALL nonessential or unrecognized extensions on the Add-ons page. Either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and, before restarting, see the next point.

This article describes how you can check for and remove a user.js file if you have one: How to fix preferences that won't save.

By the way, some external software has a browser protection or home page protection setting that will override your changes made from within Firefox. I think this has been discovered in Advanced SystemCare and perhaps one other one recently. If you want to continue using that feature, you need to release the lock temporarily to allow your change, and then lock it again afterwards.

I have the same problem and can't find a solution anywhere. this solution can't help someone who can't load Firefox at all. There's no way to get to the reset Firefox link!

Hi tpickard1, do you have Windows?

Could you try starting Firefox up with a blank page. On the Start menu, either the search box or the Run dialog, paste the following and press Enter:

firefox.exe "about:blank"

Does that get Firefox going?

Hi, yes that gets me a blank page with Firefox and its button at the top. Now what should I do, do you know? Is there some way I can get rid of this URL invalid thing when I just click on the icon to start up? Thanks for getting me this far.

Hi tpickard1, could the problem be your home page? You can reset your home page and your search engine back to their original settings by running this add-on:

https://addons.mozilla.org/en-US/firefox/addon/searchreset/

Speaking of add-ons, in case a bad extension caused this problem in the first place, review your list for anything nonessential or unrecognized. You can open up the Add-ons page using either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

The The address isn't valid The URL is not valid and cannot be loaded message shouldn't prevent Firefox from starting, as it only indicates a problem with the URL that can be bypassed.
So if you aren't able to launch Firefox then you have a different problem.

Does Firefox crash?

Are there any specific error message shown?

If that is the case then could you please attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Can you start Firefox in Safe Mode?

You can use one of these to start Firefox in Safe Mode:

• On Windows, hold down the Shift key while starting Firefox with a double-click on the Firefox desktop shortcut
• On Mac, hold down the Options key while starting Firefox

• Help > Restart with Add-ons Disabled

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Hi. thanks very much for this reply. You're right, I didn't use the correct language. \ Fx does load, but I get that URL message when I click on the icon to get to it on my homepage. The prior answer solved the problem since it did have to do with my homepage, for some reason. I got the add-on and everything's fine now. I don't think I need to try your suggestions at this point. I sure wish I knew why this happened all of a sudden though. If you have time and the inclination, perhaps you could tell me what it means and how to bypass the problem with the URL.... Toni

Hi Toni, if it happens again, check what home page is listed in the Options dialog. This article describes where to find it: Startup, home page, tabs, and download settings. That may provide some insight into what is changing it.

The way to proceed in cases like this is to check the URL that is getting opened and modify or reset those page(s) either via Tools > Options or by going to the about:config page and reset involved pref(s) directly or, in case of an issue with startup, check the target field in the desktop shortcut.

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 use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

Thanks for your reply cor-el. I'll keep the advice against the unwanted possibility that a similar problem arises. May I be spared!

The Mozilla community is a terrific group of people and a wonderful resource for a nudnik like me.

Toni