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I got "Unexpected error" when trying to sign in to Firefox Sync.

  • 37 replies
  • 2 have this problem
  • 71 views
  • Last reply by FredMcD

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I have no such issue with my office computer.

Please help.

Chosen solution

I got it fixed finally. Both PCs.

Just by powering off and back on the WiFi modem. That's it!

Still, thanks to all for the help rendered.

Read this answer in context 👍 0

All Replies (17)

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idro90 said

Unexpected error also today

I just sent an email to stomlinson ......

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2g01UviG said

I have no such issue with my office computer. Please help.

Is it possible to take the home computer to the office to see if the same problem manifests? Or tether to a mobile connection from the home computer? I am wondering if there is a networking issue at play.

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My company will not allow regardless of whether it is desktop or laptop. Security is paramount. I am afraid have to scrap this idea.

Both my home pcs have this issue, so networking could be suspect. But other users have reported the same problem.

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stomlinson said

2g01UviG said
I have no such issue with my office computer. Please help.

Is it possible to take the home computer to the office to see if the same problem manifests? Or tether to a mobile connection from the home computer? I am wondering if there is a networking issue at play.

Will it help if I copy my office Firefox profile files to my home pc? I noticed that the office Firefox password for this account login is not the same as the home one. It does not show the password, but more like codes.

Modified by 2g01UviG

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If you have a laptop, go to a location away from the house with the laptop and use a public WiFi. Is the problem still there?

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Sorry, I don't have a laptop.

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I don't want to tie you guys up trying to solve my problem. I have been using Firefox since its inception and will continue to use it regardless of the outcome of this issue.

It is ok to move on if the solution needs more time.

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2g01UviG said

Will it help if I copy my office Firefox profile files to my home pc? I noticed that the office Firefox password for this account login is not the same as the home one. It does not show the password, but more like codes.

It's really hard to say what the issue is. If you sign in to https://accounts.firefox.com using Chrome, Safari, Opera or IE on the same computer, do you still see "Unexpected error" caused by CORS?

If yes, then there might be a network problem. If no, it could be a profile problem, but that seems unlikely if you have the same problem when creating a new profile or when using a different device on the same network.

Do you have Firefox on your phone? If so, are you able to sign in there?

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stomlinson said

2g01UviG said
Will it help if I copy my office Firefox profile files to my home pc? I noticed that the office Firefox password for this account login is not the same as the home one. It does not show the password, but more like codes.

It's really hard to say what the issue is. If you sign in to https://accounts.firefox.com using Chrome, Safari, Opera or IE on the same computer, do you still see "Unexpected error" caused by CORS?

If yes, then there might be a network problem. If no, it could be a profile problem, but that seems unlikely if you have the same problem when creating a new profile or when using a different device on the same network.

Do you have Firefox on your phone? If so, are you able to sign in there?

Using both Edge and Android Firefox to login to https://accounts.firefox.com caused : "Unexpected error".

Modified by 2g01UviG

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Note that the chrome://FirefoxAccounts entry in the password manager stores the Firefox Sync account authentication data (kA and kB) in JSON format. This is different than the name and password you enter if you directly access accounts.firefox.com


In case of issues with Sync you can try this:

Disconnect from Sync and Reconnect to Sync again. You can disconnect from Sync by clicking the e-mail address in the "3-bar" Firefox menu button drop-down list or go to "Options/Preferences > Sync".

Delete the signedInUser.json file in the Firefox profile folder and delete the Weave folder (Sync was formerly named Weave) with Firefox closed.

Remove an existing chrome://FirefoxAccounts entry in the Firefox Password Manager.

If that isn't enough then delete the prefs.js files to reset all prefs and maybe also delete the compatibility.ini file to reinitialize the profile.

Delete and re-create the Firefox account or change the Sync password. Note that changing the Sync password will wipe all data stored on the Sync server.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

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I use only firefox, but I have the problem too. I tried also with chrome and edge just to understand if if could be the browser but nothing change.

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idro90 2g01UviG Try contacting your ISP to test your service.

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I solved fixing open DNS also on my pc and not only on my modem. Don't know why, but it works.

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That was very good work. Well done.

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idro90 said

I solved fixing open DNS also on my pc and not only on my modem. Don't know why, but it works.


Could you elaborate on how you did that to a newbie?

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Chosen Solution

I got it fixed finally. Both PCs.

Just by powering off and back on the WiFi modem. That's it!

Still, thanks to all for the help rendered.

Modified by 2g01UviG

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That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

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