Hellow,
I started getting below error after signing in using google.
signInWithCredential failed: First argument "credential" must be a valid credential.
"firebase": "^5.0.1",
"react-firebaseui": "^1.2.3",

Looks like a duplicate of https://github.com/firebase/firebaseui-web/issues/367
having same issue
You are probably using conflicting versions of firebase library. We have changed our dependency to be a peerDependency but have not deployed these changes yet.
@bojeil-google in the meantime, what version should firebase be at to work with react-firebaseui?
If you are using FirebaseUI v3, you should use firebase v5 with it.
moving from firebase version ^5.0.1 to ^4.13.1 fixes the problem.
My angular app give me this error after upgrading firebase to 5.0.4 and firebaseui to 3.0.0. I am now going to delve into source code and/or strip down the app to its bare bones, but meanwhile any bright ideas about things to try?
I would have just never touched this except for the fact there was a different bug in firebaseui that I was recommended to upgrade to 5.0.4 to fix. In any case it would be very hard to go back now since I have updated to the latest rc of angularfire2, which is dependent on 5.0.4, and that involved breaking changes which required code modifications.
@rtm Are you using NPM or CDN to include firebase library? If NPM, could you use npm ls to provide your dependency list?
@wti806 It turns out I had not fully updated my dependencies, and now things look good. Thanks for following up.
There was some issues here with earlier version of the Firebase SDK v5 which have now been fixed. Closing this.
Most helpful comment
moving from firebase version ^5.0.1 to ^4.13.1 fixes the problem.