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Firefox version conflict detected

  • 11 replies
  • 1 has this problem
  • Last reply by jscher2000

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Hi all,

There is a recurring error annoying me, every two days (more or less), I get the message below, then it is needed to create new profile and configure it again. Firefox version: 77.0.1 (64-bits) SO: Windows 10

English You have released an older version of Firefox Using an older version of Firefox can corrupt bookmarks and browsing history already saved in an existing Firefox profile. To protect your information, create a new profile for this installation of Firefox.

'Português (my installation) Você lançou uma versão mais antiga do Firefox Usar uma versão mais antiga do Firefox pode corromper favoritos e o histórico de navegação já salvos em um perfil existente do Firefox. Para proteger suas informações, crie um novo perfil para esta instalação do Firefox.'

How can I fix it? I already have reinstalled it several times.

Thanks and regards, Marcos

Chosen solution

All Replies (11)

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hello mviudes,

follow this link


i hope resolve the problem

Thank you!


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please go through the given link and do the following steps :

Troubleshoot and diagnose Firefox problems

thank you...


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Hi Marcos, please ignore that toll-free number spam. That is not official support and we don't know what will happen to you if you let them into your system!


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Hi Marcos, can you check whether you have multiple installations of Firefox? For example, on both of these paths:

  • C:\Program Files\Mozilla Firefox
  • C:\Program Files (x86)\Mozilla Firefox

That could cause this problem is different versions are starting up on different days. Before cleaning that up, you may need to take a few preparatory steps. In particular, if you have Microsoft Office installed, please change your Windows 10 default browser to Edge before removing any Firefox installation, otherwise Office may get very confused.


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Thanks guys!

I have manually removed all existent profiles (firefox.exe -P) and create a new one. I will let you know in a few days if the problem is gone. Regarding installation folders, I got just one.

Best regards!


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Hi, suggest empty cookies, clear cache

Here are the usual suggestions:

When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Bypass Firefox's Cache

Use Ctrl+Shift+r to reload the page fresh from the server.

Alternately, you also can clear Firefox's cache completely using:

"3-bar" menu button (or Tools menu)-- > Options -->

On the Network mini-tab > Cached Web Content : "Clear Now"

If you have a large hard drive, this might take a few minutes.

Options --> Security & Privacy-- > "Manage Data"

In the dialog that opens, you can remove the site's cookies individually.

Then try reloading the page. Does that help?

In case one of your extensions is involved, could you test the page in Firefox's Safe Mode? That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Troubleshoot Firefox issues using Safe Mode.

You can restart Firefox in Safe Mode using either:

   "3-bar" menu button > "?" button > Restart with Add-ons Disabled
   Help menu > Restart with Add-ons Disabled 

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset). 

Any difference/fixed ?


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Unfortunately the issue is still happening. I have tried what you guys suggested with no luck. Really weird, never had this problem in the past. It looks like some related to this local installation.


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Hi Marcos, could you clean out the updates folder in case there is an old update "stuck" in there. To find that, you need to explore the following path:


AppData is a hidden folder, so one way to jump into AppData\Local is to use a shortcut path:



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Hi Jefferson,

Did not find the folder "update". Neither on %LOCALAPPDATA%/mozilla nor %LOCALAPPDATA%/mozilla/firefox.

Thanks and regards


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Chosen Solution

It worked for me. Does it make sense?

Thanks! Best Regards.


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Hi Marcos, it doesn't really explain why the problem happened, but if it allowed using your upgraded profile in an older version, that's good. But why are there two versions? Still a mystery.


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