I'm having this issue with the latest Firefox Beta (4.0b12). I had faced similar issues with 4.0b11 too. :(

As per the following page this is supported on 4.0b12 - http://www.mozilla.com/en-US/mobile/sync/

I had to call AT&T and went through a whole lot of rig a ma role to be able to connect to the internet again. It was a nitemare. I was on the phone for 2 hours with a very understanding young man. Because of my limited hearing, phone conversations are a real hassle. Now I close down my computer each time I walk away from it, because I'm afraid I'll have the same problem. Is there something wrong with the new Beta4?

Had this problem too after installing a beta of Firefox 4. It turned out that the installation procedure must have "FIPS activated" on my installation (I guess, Sync is using some non-Approved algorithms which are not available when FIPS mode is activated). Check settings in the Firefox options, Advanced, Encryption, Security Devices, Disable FIPS if enabled. Worked for me.

I started having this problem after the download of the new Firefox 5.0. No solutions posted have worked so far. FIPS is already disabled.

Same problem happening here with Firefox 5 on Mac OS X 10.6.8. It just started recently, and is only affecting one of two computers in the same house that use Sync.

I solved this problem by logging out of Sync and logging back in. You will need your Account, Password, and Sync Key to do that.

1. From Preferences choose Sync.
2. Then click "Deactivate This Device" link.
3. Click the "Reset all Information" button.
4. Click "Set Up Firefox Sync" button.
5. Click "Connect" button under "I already have a Firefox Sync Account."
6. On the "Add a Device screen, click the "I don't have the device with me" link.
7. Enter your Account, password, and sync key.

Firefox is ready to sync and you're good to go! Now you need to make sure your devices can connect, but they are probably still connected to your account OK.

After having this problem i decided to tinker around with Firefox settings and got it to work. This is how i did it: Go Tools/Options/advanced Then in protocols check mark the box next to Use SSL 3.0 and try to set up sync again, it should work now.

Deactivating and reactivating the Sync device is the only suggestion that worked for me.

I have no idea what caused the problem to suddenly appear.

Anyway, thanks for this.

Jerry

I couldn't find an Options under Tools in Firefox 6.0.2, Fedora 15. The only optiony thing is Edit/Preferences.

Having this issue too in 7.0.1

Me, too. I get the error message, but everything still works. I just close the message.

Me too in Firefox 7.0.1. Where can I find my account login and sync key?

This issued effected my work PC today (7.0.1) - resolved by deactivating/activating.

It's happening again with Firefox 8.0. Maybe Mozilla's dev team could concentrate a little more on fixing nonsense like this; the error bar just keeps coming up no matter how many times I click on it!

How often is the new Firefox trying to sync and why? How can we check on the server to see if it is up or down? And why can we not disable the stupid error bar outright, or at least get it to shut up for an hour or so? I don't need the thing every 30 seconds.

Go to Tools, Options, Sync, Manage Account, My Sync Key, Generate New Sync Key, Change Sync Key. This should fix problem.

I had this problem and then noticed my date in Windows was set to 2011. This caused the security certification on mozilla to register as expired. I changed the date to days date and solved the problem.