Classic Universal Login MFA Prompt Fails on iOS when Switching Apps

Universal LoginMulti-factor Authentication

Last Updated: Sep 10, 2025

Overview

When users navigate out of the app during a Multifactor Authentication (MFA) challenge, like to open an Authenticator App to copy and paste an MFA code, the MFA challenge is terminated and throws a 401 error.

Applies To

Classic Universal Login
Multifactor Authentication (MFA)
iOS Devices

Cause

This is a limitation of Classic Universal Login due to a lack of control over this behavior, where there is a chance an IOS update has changed the behavior of minimizing apps that require cross-origin polling. iOS is terminating the requests, not Auth0 services.

Solution

The recommended solution is to move to New Universal Login.