Authorisation Error Error 400: redirect_uri_mismatch

[#1]

Dear experts,

while implementing executing Oa2c_grant in system and click on button Request OAuth 2.0 Tokens,

i am getting this error. I am tottaly stuck with that.

The redirect_uri passed in the authorization request does not match an authorized redirect URI for the OAuth client ID. Review authorized redirect URIs in the Google API Console Credentials page.