Code=17000 “The custom token format is incorrect. Please check the documentation.”

5
votes

I followed the steps described here : https://firebase.google.com/docs/auth/admin/create-custom-tokens

I am able to create custom tokens using the Firebase Admin SDK.

I send them back to the client iOS app to use like this :

Auth.auth().signIn(withCustomToken: customToken ?? "") { (user, error) in
  // ...
}

But I get this error :

Code=17000 "The custom token format is incorrect. Please check the documentation." UserInfo={NSLocalizedDescription=The custom token format is incorrect. Please check the documentation., error_name=ERROR_INVALID_CUSTOM_TOKEN}

I'm using Firebase Admin 5.2.0 and the Firebase iOS client 4.0.0

Any idea?

2
firebasefirebase-authentication
Check this post for how to debug this: stackoverflow.com/questions/45110441/… Keep in mind the custom token lifetime is limited and it could expire if you are storing and reusing it. – bojeil
I already managed to request newer one if it's expired, but my issue is that the token never works – Monta
Ok, wanted to get that out of the way. Check the decoded format of the custom token as described in that link. – bojeil
@bojeil The token is correctly decoded with the correct data using the debugger jwt.io – Monta
Make sure the client side project matches the service account that generated that custom token. Try sending the token with the REST API: firebase.google.com/docs/reference/rest/auth/… If that doesn't help, you should contact Firebase Support. – bojeil

2 Answers

0
votes

I try a lot time to solve it.. and I found something interesting. The custom_toke end with "%3D%3D", this is not a valid, you need to replace is with "==".. and it will work good.

0
votes

After checking the token and its lifetime, it turned out that a mismatch in system-time was the problem in our case.

After setting the timezone and the time to 'automatic', the problem was solved.