Sync requires the user to have the email address that was last used by Sync to be active. If you can't access that email account, there is no way to sign into Sync / Firefox Account. The only "fix" is to create a new Sync account with a current email address - but you won't be able to access your old Sync data. A new account will allow you to use Sync going forward.

Any chance that you have another Firefox installation that has your Sync data? If not, you weren't using Sync as intended; i.e. to synchronize data across multiple devices. Sync wasn't intended to be used as a backup media for a single Firefox installation.

As far as logging into this forum, nothing has changed as far as Username / Password in quite a long time - as in like close to 7 years now.

You can request help here for your old account at this support forum: https://support.mozilla.org/en-US/forums/contributors Title should be like: Request for Admin Help with SuMO Account Password

With respect to "Any chance that you have another Firefox installation that has your Sync data?" the answer is yes, I have it on two desktop computers and my tablet, and they're all synced. But how to transfer it to my new laptop? My old laptop was also synced, but it died and I'm trying to set up FF on my replacement laptop.

The problem isn't in entering my sync information on my new laptop, it comes from the confirmation email being sent to a defunct email account. Am I the first person to ever have used the FF sync data function and changed their email address? Perhaps the sync implementation wasn't very well thought out?

Any suggestion on how to request a fix to this this shortcoming would be appreciated.

In the mean time, I found a suggestion to close FF and copy my profile from the appropriate application data locations to the new machine. Is this advisable or can you suggest a more appropriate work around?

Thanks for your help!

If you can't use Sync for any reason then you can transfer files manually via an USB jump drive.

You can copy files like these to the current Firefox profile folder to recover specific data.

• bookmarks and history: places.sqlite
• bookmark backups: JSON backups in the bookmarkbackups folder
• SQLite files like cookies.sqlite (cookies) and formhistory.sqlite (saved form data)
• logins.json and key3.db (decryption key) for Passwords saved in the Password Manager
• cert8.db and possibly cert_override.txt for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words you added to the spelling checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other Site Preferences
• sessionstore.js for open tabs and pinned tabs and tab groups

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

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

See also:

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile

The email address is the primary identifier for Sync accounts, and as such it can't be changed. It's been like that since Firefox 4.0 in March 2011; and prior to Sync being a built-in feature in Firefox 4.0 the account had a separate username and the email address was used only for new account verification and could be changed as needed. Overall, this hasn't been a big issue until very recently, although when it was changed in the months before the release of Firefox 4.0 - I knew that change to using the email address as the primary identifier would create problems down the road. But hey, I'm just a user like you I have no "say" in the cockamamie schemes Mozilla comes up with. I had to quit using Sync for almost a year after that change because the was no backward compatibility to Fx 3.6 (and the Weave extension that preceded Sync being built-in) which I had to keep using on an old EeePC Netbook that was my 2nd device as it couldn't handle Firefox 4.0. The confirmation email is a fairly new feature, at least as it is now used. I have heard mention that allowing the email address that is used to be changed is something being considered or in the planning stages now. IMO, that might entail a 3rd factor being added as the primary identifier - additional to the email address and the password.

As far as how to handle your dilemma now. 1. Disconnect those other three devices from your current Sync account. 2. Create a new Sync account on one of the two desktop PC's. 3. Allow Sync to retrieve your data from that desktop PC. 4. Then connect the other two devices to the new Sync account. 5. Finally, connect that new laptop to the new Sync account.