I get an error that says: "Invitation redemption failed;

The behavior matches a Microsoft Entra B2B invitation redemption problem where the sign-in account does not match the account that was invited, or there is a conflict between identities.

Use these steps to resolve it:

1. Sign out of all Microsoft accounts
   • In the browser where the error appears, sign out from all Microsoft sites (for example, account.microsoft.com, portal.office.com, myapps.microsoft.com).
   • Close all browser windows.
2. Use a private/incognito browser session
   • Open a new InPrivate/Incognito window.
   • Open the original invitation email again and click the invitation link from inside this private window.
3. Make sure to use the exact invited account
   • When redirected to sign in, use the same email address that received the invitation.
   • If prompted to choose between a “Work or school” and a “Personal” (Microsoft) account with the same email address, select the account type that was originally used to register for the service (typically “Work or school” for organizational access).
4. If you are asked to “switch accounts” again
   • Follow the “switch accounts” link and explicitly choose the invited account (the address that received the invitation) rather than any other Microsoft account already on the device.
5. If the error persists, contact the inviting organization’s admin
   • Ask the site/tenant administrator to:
     • Confirm that the invitation is still valid and, if needed, resend it.
     • Check for common B2B redemption issues:
       • The invited user’s domain may disallow email-verified users from being created.
       • The external user might not exist in a federated domain.
       • There might be a proxyAddress conflict with an existing user.
   • These issues must be fixed by the admin in the inviting or home tenant before redemption will succeed.
6. If the email address is used both as a personal Microsoft account and as a work/school account
   • This overlap can block creation of the guest/work account. The typical remediation is to rename the personal Microsoft account to a different email alias so that the work/school identity can be used cleanly for invitations and sign-in.

If, after these steps, the same error continues, provide the full error text and correlation details (if shown) to the inviting organization’s IT/admin so they can investigate the B2B invitation redemption in Microsoft Entra ID.

References:

• B2B collaboration invitation redemption
• Troubleshoot common issues with Microsoft Entra B2B collaboration
• How to Troubleshoot Common Issues