Are you using the same email address to login to your Firefox account?

• https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer

Can you login to the Mozilla Account via this web page? In case of issues, try to login to the Mozilla Account via this website using the email address and password.

• https://accounts.firefox.com/signin
• https://accounts.firefox.com/settings

Thanks for the response. Yes, using the login link, I can log in to my Mozilla account, view my profile, and access my account settings. but that does not log me in to the browser itself. When I open the browser, or click on the profile icon at the top left and click "sign in to sync," it opens the login dialog window. When I enter the password, the dialog disappears for an instant, then reappears with the password field blank. I can enter the password repeatedly and get the same result every time. I cannot find any way to sync the laptop with my Mozilla account and get access to saved passwords, etc.

The pop-up dialog does not ask for an email address--only the password.

That is the Primary Password prompt that is needed to unlock the Password Manager. Firefox needs to unlock the Password Manager as it want to store the Sync credentials in logins.json in the Firefox profile folder to be able to login the next time you start Firefox.

• https://support.mozilla.org/en-US/kb/use-primary-password-protect-stored-logins