Firebase Google SignIn failed - "Audience Mismatch" - swift

Question

I have implemented Google sign in via Firebase and followed proper documentation: https://firebase.google.com/docs/auth/ios/firebaseui
I am using,
- FirebaseUI/Auth (8.5.1):
- Firebase/Auth (~> 6.0)
- GoogleUtilities/UserDefaults
- FirebaseUI/Google (8.5.1):
- FirebaseUI/Auth
- GoogleSignIn (~> 5.0)
COCOAPODS: 1.9.3
XCode - 12
So, my Appdelegate.swift would contain following code in didFinishLaunchingWithOptions...
FirebaseApp.configure()
And presenting SignIn UI when user presses a special button on Login view controller using below code,
if let authController = authUI?.authViewController() {
self.authController = authController
self.present(authController, animated: true, completion: nil)
}
LoginViewController.swift would have following code into viewDidload()
authUI?.delegate = self
let providers: [FUIAuthProvider] = [
FUIGoogleAuth()
]
authUI?.providers = providers
where authUI is declared as property for LoginViewController => let authUI = FUIAuth.defaultAuthUI()
I have only added Google SignIn for now so only one provider added here.
Now when my SignIn Auth UI is presented, Google SignIn button is shown and I am able to log into my Google account but when didSignInWith authDataResult is executed from FUIAuthDelegate, I get to know I am receiving an error post successful Google Account Login.
Error Domain=FUIAuthErrorDomain Code=2 "(null)" UserInfo={FUIAuthErrorUserInfoProviderIDKey=google.com, NSUnderlyingError=0x600000a08720 {Error Domain=org.openid.appauth.general Code=-15 "Audience mismatch" UserInfo={NSLocalizedDescription=Audience mismatch}}}
Is there anything I am missing?
I have already setup URL schema into info.plist and not getting any clue on how this kind of error is being generated.
Further as an update to #frank-van-puffelen,
I have confirmed proper info.plist is added or not.
My Info.Plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>CLIENT_ID</key>
<string>847792004435-gdisqis038je5q8rr1on4ti7df09nvht.apps.googleusercontent.com</string>
<key>REVERSED_CLIENT_ID</key>
<string>com.googleusercontent.apps.847792004435-gdisqis038je5q8rr1on4ti7df09nvht</string>
<key>API_KEY</key>
<string>AIzaSyDRrYM2h1wOEdKHZtOM-M904oBwrXnaO3E</string>
<key>GCM_SENDER_ID</key>
<string>847792004435</string>
<key>PLIST_VERSION</key>
<string>1</string>
<key>BUNDLE_ID</key>
<string>com.Speare.StashAlpha</string>
<key>PROJECT_ID</key>
<string>stash-demo-11379</string>
<key>STORAGE_BUCKET</key>
<string>stash-demo-11379.appspot.com</string>
<key>IS_ADS_ENABLED</key>
<false></false>
<key>IS_ANALYTICS_ENABLED</key>
<false></false>
<key>IS_APPINVITE_ENABLED</key>
<true></true>
<key>IS_GCM_ENABLED</key>
<true></true>
<key>IS_SIGNIN_ENABLED</key>
<true></true>
<key>GOOGLE_APP_ID</key>
<string>1:847792004435:ios:867e5fb8113b83b48f55a6</string>
<key>DATABASE_URL</key>
<string>https://stash-demo-11379.firebaseio.com</string>
</dict>
</plist>
Screenshot of project which is targeted for login,
We can clearly check here Project ID matches in info.plist as well as on Sign In screen.
Now in Firebase console, if we check, project ID matches and below is info.plist download button from where I can take latest info.plist.
Let me know if there is anything we can confirm info.plist does not match with target project.

Answer 1

This error message usually means that you're trying to sign in to a different project than what the token was minted for. So you might want to check if you have the info.plist for the correct project, and that you're set up you OAuth sign in against that same project.