AADSTS50034 — "The user account does not exist in the directory. To sign into this application, the account must be added to the directory." The username entered does not resolve to any user object in the tenant that was asked. Unlike AADSTS50020 there is no successful upstream authentication — the lookup itself failed.
AADSTS50034
User account does not exist in the directory
What it means
Common causes
Typo in the username, or the user entered an email alias / SMTP address that is not their UPN.
The request targeted the wrong tenant (single-tenant authority pointing elsewhere, or the user picked the wrong account entry).
The account was deleted, or in hybrid setups has not (yet) synced to Entra ID.
Sign-in with an alternate email is expected but 'email as an alternate login ID' is not configured.
How to fix it
Verify the exact UPN:
Get-MgUser -UserId user@domain.com(Microsoft Graph PowerShell) or search in Entra admin center > Users.In hybrid environments, confirm the user is in scope for Entra Connect/Cloud Sync and that the last sync succeeded.
Check the authority/tenant in the failing request matches the tenant where the user lives.
If users habitually sign in with a secondary email, either educate on UPN sign-in or configure email as an alternate login ID.