AWS Amplify Auth.updateUserAttributes() clear localStorage/sessionStorage - amazon-web-services

Question

I am writing a web-based app that uses AWS Cognito as the authentication service. I use 'aws-amplify' to implement the client-app.
I am using Auth.updateUserAttributes() to update a custom attribute of users on Cognito. However, I found that the call of this function would clear all the Cognito-related items, including idToken, refreshToken, and accessToken stored in localStorage. As a result, the web app behaves like sign-out.
Here is the code about Auth's configuration
Amplify.configure({
Auth: {
userPoolId: process.env.REACT_APP_AWS_COGNITO_USER_POOL_ID,
region: process.env.REACT_APP_AWS_COGNITO_REGION,
userPoolWebClientId: process.env.REACT_APP_AWS_COGNITO_APP_CLIENT_ID,
storage: window.localStorage,
authenticationFlowType: 'CUSTOM_AUTH',
},
});
and the code I wrote to update the user's attribute. (I followed the example code from the amplify docs https://docs.amplify.aws/lib/auth/manageusers/q/platform/js/#managing-user-attributes)
let user = await Auth.currentAuthenticatedUser();
console.log(JSON.stringify(localStorage)); // it outputs the localstorage with idToken,
// refreshToken, accessToken and other items
// start with 'CognitoIdentityServiceProvider'
const result = await Auth.updateUserAttributes(user, {
'custom:attributes_1': '123456789',
});
console.log(result); // OUTPUT: SUCCESS
console.log(JSON.stringify(localStorage)); // Only 'amplify-signin-with-hostedUI'.
// idToken, refreshToken, accessToken and
// other items were gone. No key, no value.
After the last line, I could not interact with the web page anymore. If I refreshed the web page, I found I had signed out and had to sign in again.
It was still the same if I changed the storage for Auth from localStorage to sessionStorage.
Here are my questions:
Is this kind of behavior normal? Does Auth.updateUserAttributes() leads to a force sign-out?
If it's true, is there any way to avoid a mandatory sign-out?
If it's not, what's wrong with my code or configuration? Or should I do some specific configuration for the Cognito service?
Thanks a lot!

Answer 1

Well, I figured it out after reading the source code of aws-amplify.
Behind the call of Auth.userUpdateAttributes, amplify will finally call CognitoUser.refreshSession(refreshToken, callback, clientMetadata) (https://github.com/aws-amplify/amplify-js/blob/f28918b1ca1111f98c231c8ed6bccace9ad9e607/packages/amazon-cognito-identity-js/src/CognitoUser.js#L1446). Inside this function, amplify sends an 'InitiateAuth' request to Coginito. If an error of 'NotAuthorizedException' happens, amplify calls clearCachedUser() that delete everything I mentioned in my question from the localStorage.
There was an error of 'NotAuthorizedException' happening and reported by the network work monitor of Chrome Browser'. I thought it was generated after the sign-out-like behavior. However, it turned out to be triggered because no deviceKey was passed to the request's parameters.
So the whole story was:
I set remember device options in Cognito;
I used 'CUSTOM_AUTH' as the authentication flow type;
When a user successfully signed in to my application, Cognito didn't give the client the deviceKey because of the 'CUSTOM_AUTH' authentication flow type.
When Auth.userUpdateAttributes() was called, CognitoUser.refreshSession() was called behind it. It attached no deviceKey to Cognito when it sent ana request to asked Cognito to refresh the token. The Cognito rejected the request with an error of 'NotAuthorizedException'. The CognitoUser.refreshSession() handled the error and called clearCachedUser() to delete the stored tokens and other info from the localStorage.
My final solution is to turn off the remember device option since I have to use 'CUSTOM_AUTH' as the authentication flow type according to my application's functional requirements.
According to https://aws.amazon.com/premiumsupport/knowledge-center/cognito-user-pool-remembered-devices/, the remember device function only works when the authentication flow type is set as 'USER_SRP_AUTH'.