Firefox 90 introduces the next version of SmartBlock, the browser’s tracker blocking mechanism built into its private browsing and strict modes, which now has improvements designed to prevent buttons that let you log into websites using your Facebook account from breaking, Mozilla announced on Tuesday.
SmartBlock was first introduced with Firefox 87 in March, and if you aren’t familiar, here’s Mozilla’s description of how it works, from the company’s blog:
SmartBlock intelligently fixes up web pages that are broken by our tracking protections, without compromising user privacy.
SmartBlock does this by providing local stand-ins for blocked third-party tracking scripts. These stand-in scripts behave just enough like the original ones to make sure that the website works properly. They allow broken sites relying on the original scripts to load with their functionality intact.
Sometimes, though, the feature would break Facebook login buttons. In a new blog post, Mozilla’s Tom Wisniewski and Arthur Edelstein explain why this would happen, using an example of trying to log in to Etsy.
“Prior to Firefox 90, if you were using a Private Browsing window, when you clicked on the ‘Continue with Facebook’ button to sign in, the ‘sign in’ would fail to proceed because the third-party Facebook script required had been blocked by Firefox,” they write.
With Firefox 90 and SmartBlock 2.0, though, you should be able to use Facebook login buttons all while SmartBlock 2.0 still blocks cross-site tracking. On the updated browser, “initially, Facebook scripts are all blocked, just as before, ensuring your privacy is preserved,” they write. “But when you click on the ‘Continue with Facebook’ button to sign in, SmartBlock reacts by quickly unblocking the Facebook login script just in time for the sign-in to proceed smoothly.”
Firefox 90 is launching Tuesday.
