Two-factor Authentication (2FA) – Top Asked


2FA Top Asked Questions

What is your scenario?

New Student / Staff
  1. I am a new student / staff.  How to register my account for 2FA?Please refer to the step-by-step guide. In case you haven’t collected your OnePass Account, please:
    Student – refer to step 1 of the new student guide.
    Staff – refer to step 1-2 of the new staff guide.
  2. I was unable to complete the registration and now I cannot log in to my email. What can I do?
    2FA Error page
    This may happen if the registration is not completed on time, or your computer / browser freezes during the registration.
    Please refer to the step-by-step guide for resolution.


Personal Account
  1. I got a new phone.  How to transfer my 2FA account to the new device?

    Please refer to the step-by-step guide.
  2. I do not have my phone on hand / out of battery.  How to get around the 2FA login prompt?

    Please refer to the step-by-step guide.

  3. How to check my email after 2FA enrollment?Visit CUHK Office 365 using any web browser. During login, you need to verify your identity by simply respond to a push message or enter a passcode. For details, please refer to the step-by-step guide.
  4. How to log in VPN after 2FA enrollment?You will receive a push message automatically after entering your username and password.  This is slightly different from other web application systems (such as email) in which you can choose to push a message or enter a passcode. Please make sure your mobile device has a stable Internet connection when you’re connecting to VPN.Refer to user guides below, particularly the No Push Messages section if you did not receive a push message during the connection.

    CUHK VPN: Windows | Mac | iOS | Android
    SSL VPN: Windows | Mac | iOS | Android

Departmental / Project / Organization Account
  1. I have a departmental / project / organization account.  How to setup 2FA for my colleagues / teammates?Please refer to the step-by-step guide.
  2. Can I use the same mobile phone to authenticate my staff / student account and project / organization account?Yes, you can configure multiple accounts in Duo Mobile App for 2FA authentication.
    Please refer to this knowledge article for details.
  3. I do not have my phone on hand. How to get around the 2FA login prompt?Please check if you still have the Rescue Code saved when you first enroll into 2FA for the Departmental / Project / Organization account. If so, you can use it to generate the Bypass Code by following the steps below:
    1. Visit using any web browser.
    2. After signed-in using the Departmental / Project / Organization account, click BYPASS CODE tab > I HAVE A RESCUE CODE ON HAND. > insert one of the saved  Rescue Code > SUBMIT.

    Otherwise, please contact us for assistance.

Other Questions
  1. Can I use Duo 2FA from mainland China and overseas?Yes, and specifically:
    • Push message works when your mobile phone is connected to the Internet
    • Use passcodes generated in Duo Mobile app if your phone is not connected to the Internet
  2. I received an authentication request, but I am not signing in.  What should I do?That means someone may know your password.
    • For personal account: decline the request and change your OnePass password immediately
    • For departmental / project / organization account: decline the request, ask if your colleagues / teammates sent out the request by error.  Change the account’s password if in doubt


  1. When will the new version of DUO Mobile release?

    DUO will release a redesigned version of the DUO Mobile v4 worldwide on the following timeframes.

    • For iOS: October 11 through 18, 2021
    • For Android: October 11 through 15, 2021

    The exact release time is arranged by Apple App Store / Google Play Store.

  2. Do I need to do anything?No. The current version (v3.x) of DUO Mobile will still work.If you have automatic apps updates enabled on your devices, DUO Mobile v4 will be updated automatically via Apple App Store and Google Play Store. You can also update your Duo Mobile manually.You do not need to re-enroll in DUO or do any settings after the update.
  3. I am using an older version of iOS/Android. What will happen?DUO Mobile 4 supports
    • iOS: 14 or above
    • Android: 10 or above

    If you are using devices with an older version of iOS/Android and have DUO Mobile already installed, you will still be able to use the app normally, and the app will stay in v3.x version.

  4. What is changing and why?

    The user interface is redesigned to make your device set up and login experience better. For example, the Approve button in the push approval prompt is now on the right to yield a more natural and fluid experience.
  5. What is NOT Changing?The core functionality of Duo Mobile is not changing. You will continue to be able to:
    • Receive a Duo Pus
    • Use passcodes
    • Add, edit, reorder, and remove accounts, and
    • Anything else you can do in the current version of the app

  6. Where can I obtain more information about the update?Please visit our dedicated website for details.