Firebase Auth login dead in incognito: enable third-party cookies

TL;DR

No code changes on the app side; users just could not log in anymore. Community-confirmed fix: turn on third-party cookies for the incognito session.

Steps

1. Issue firebase/firebase-js-sdk#3004 (closed, 50 comments): Firebase Auth logins stopped working for users browsing in Chrome incognito mode (SDK 7.13.1). No code changes on the app side; users just could not log in anymore.
2. Community-confirmed fix: turn on third-party cookies for the incognito session. Commenter andrewhamili reports that flipping the third-party cookie setting on in incognito resolves it. Firebase Auth depends on third-party cookies for the session flow, and Chrome's incognito defaults block them, so users who hit a dead login in private browsing should check that setting before anything else.

When to use

You are seeing this: Issue firebase/firebase-js-sdk#3004 (closed, 50 comments): Firebase Auth logins stopped working for users browsing in Chrome incognito mode (SDK 7.13.1). Use this skill when you run into "Firebase Auth login dead in incognito: enable third-party cookies".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: SDK 7.13.1. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Sources

• https://github.com/firebase/firebase-js-sdk/issues/3004

In https://github.com/firebase/firebase-js-sdk/issues/3004, the reporter asked: Issue firebase/firebase-js-sdk#3004 (closed, 50 comments): Firebase Auth logins stopped working for users browsing in Chrome incognito mode (SDK 7.13.1). No code changes on the app side; users just could not log in anymore. The verified answer: Community-confirmed fix: turn on third-party cookies for the incognito session. Commenter andrewhamili reports that flipping the third-party cookie setting on in incognito resolves it. Firebase Auth depends on third-party cookies for the session flow, and Chrome's incognito defaults block them, so users who hit a dead login in private browsing should check that setting before anything else. Source thread: https://github.com/firebase/firebase-js-sdk/issues/3004