hello, i think you'll also have to allow third-party-cookies for the firefox accounts sign-in site to work...

Make sure that you allow cookies for the accounts.firefox.com domain if you aren't allowing cookies generally or use ask me.

Initially, I had cookie options set to 'Ask every time' and 'Never accept 3rd party cookies.' So, the cookies were the issue.

In the troubleshooting process, I also tried 'Ask every time' and 'Always accept 3rd party cookies,' but that did not work. It never prompted me to accept a cookie. So, I had to enable accepting all cookies while I did the sync setup, then change it back.

Thank you for the help!

You're welcome

How do I allow the cookies?

psop has created a new question, so lets continue there.

• [/questions/1033532]

I just reported this same issue. I was able to fix it once I opened firefox in safe mode. This disabled all my plugins and add ons. So something I had in add ons/plugins was keeping it from opening. This same blank page was happening when I opened gmail too but that also got fixed.

If you have any extensions that can block cookies or other content then check their settings.

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Note that at least you need to allow cookies for the accounts.firefox.com domain