I had working auth workflow using Lock widget (popup, google account) and signing in with customToken to Firebase. Then I had to update settings by adding one more host to “Allowed Origins (CORS)”. Initially I was getting error “invalid grant types: client_credentials” but when I chose “Client Type…

Please see the following post for a similar resolved issue: http://community.auth0.com/questions/3944/error-grant-type-password-not-allowed-for-the-clie It includes details on why this happens and how you can work around it

Error "Grant type 'http://auth0.com/oauth/legacy/grant-type/delegation/id_token' not allowed for the client" after saving settings

Error "Grant type 'http://auth0.com/oauth/legacy/grant-type/delegation/id_token' not allowed for the client" after saving settings