Workaround for MFA error when using getAccessTokenSilently with React

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1

Hi,

When using getAccessTokenSilently from the @auth0/auth0-react sdk I encountered frequent 403 errors with the error Type: Failed Silent Auth; Description: Multifactor authentication required

MFA is required but I also needed to be able to get an access token to call APIs, without prompting the user a second time after they already had authenticated with MFA previously. I had some trouble that took me several hours to figure out and I wanted to post my findings since current threads on this topic were closed, and I couldn’t find help in the Auth0 docs, I hope I can save someone else the trouble.
In our case we were using Refresh tokens as well. The solution below worked for me:

This is a working Auth0 Action similar to the same rule (which appears to be preferred over Rules)

  1. Add an Auth0 Action in the Auth0 Management panel
  2. use this code:
exports.onExecutePostLogin = async (event, api) => {
  if (event.client.name !== <your apps client name>) {
    return;
  }

  const isRefreshTokenProtocol =
    event?.transaction?.protocol === "oauth2-refresh-token";
  let authMethods = [];
  if (event.authentication && Array.isArray(event.authentication.methods)) {
    authMethods = event.authentication.methods;
  }
  const isMFAAuthenticated = Boolean(
    authMethods.find((method) => method.name === "mfa")
  );

  if (isMFAAuthenticated || isRefreshTokenProtocol) {
    api.multifactor.enable("none");
  }
};
2

Hi @zachary.willard

Many thanks for posting your findings here, it is much appreciated.

Warm regards.

3

Thank you @zachary.willard ! For those visiting this thread the solution is posted in the first post in the thread. Thank you!