I can't access my Outlook email on my new phone - keep getting error message [5ssai]

Question

This is driving me crazy! Please help...

I have an updated Android phone, uploaded Outlook and I can't past the error message [5ssai] OR 'having an authentication issue' - and it just bumps me off and I am on a never ending loop. I have done the obvious solutions of checking the internet connection, reloaded Outlook a dozen times, emptied the cashe but all I get is the 'operation attempt is invalid'.

Seriously infuriating! Can anyone please advice - thank you so much!

Answer 1

For Outlook on Android, error [5ssai] on a new phone is commonly resolved by clearing the device’s cached sign-in state and rebuilding authentication in the right order.

Try this sequence:

1. Back up Microsoft Authenticator first if it is installed.
   In Microsoft Authenticator → Settings, make sure Cloud Backup/Backup is turned on.
2. Remove old Microsoft or work accounts from Android.
   Go to Settings → Accounts / Manage accounts and delete any duplicate or old Microsoft/Work accounts tied to the previous phone setup.
3. Uninstall Outlook.
4. If Microsoft Authenticator is installed, uninstall it too.
   This clears the authentication broker state that can cause the loop.
5. Restart the phone.
   This is important so cached identity tokens are cleared.
6. Reinstall Outlook first.
7. Add the problem account first, before adding any other accounts.
8. Reinstall Microsoft Authenticator from the Play Store if needed, then restore the backup.
9. If the account is a work or school account, sign in with the full organizational account format required by the organization.
10. If Outlook keeps prompting for sign-in, install the latest version of Outlook for Android.

If the account is a Microsoft personal account, use the Microsoft sign-in helper from the support article. If it is a work or school Microsoft 365 account, use the self-service password reset page if that option is enabled by the organization.

If the account is not provided by Microsoft (for example Gmail, Yahoo, iCloud, or another mail provider), contact that email provider for sign-in help.

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