React keycloak TypeError: kc.updateToken(...).success is not a function

You are using the "old" .success() method, but you have configured using native promise types (promiseType: 'native') in init configuration.

Use the standard .then() method of standard Promise type, like in my example here, and it should work: https://github.com/dasniko/keycloak-reactjs-demo/blob/master/src/index.js#L48-L49

This is an issue with keycloak-js itself and it is set to be released with version 8.0.0 of keycloak-js.

Also react-keycloak is not using .success() internally.

See here for more details about the issue . KEYCLOAK-8938

I'd suggest you to avoid using promiseType: 'native' in your setup.