Unable to accept organization invite

Question

Hello,

I am experiencing a sign-in loop/error when trying to accept an invitation to join another organization as a guest. I already have MFA configured on my home account, but I cannot get past the security prompts to access the guest tenant.

Here is the exact flow of the issue:

1. Initial Prompt: When I attempt to log in to accept the organization invite, I receive the following message:

More information required Your organization needs more information to keep your account secure. Before making changes to your security info, you must complete multifactor authentication.

2. Error Message:
   When I click "Next" to proceed, the process fails immediately and shows the following error screen:

Account: username_mydomain.com#EXT#@inviting-org.com (redacted for privacy)
Sign-in couldn't be completed
Contact your admin for help.

Additional Context:

I already have a working Multi-Factor Authentication setup.

It seems the process is failing at the exact moment it tries to register or verify MFA for the guest tenant, blocking me from completing the sign-in. Could you please advise on how to resolve this? Does the administrator of the inviting organization need to clear my MFA settings/sessions for this specific guest profile, or is there a step I can take on my end to break this loop?

Thank you in advance for your help!

Answer 1

Hi,

The behavior you described can occur when the inviting organization requires MFA for external/guest users. Having MFA already configured in your home organization does not necessarily mean that the MFA requirement of the inviting organization will be satisfied.

For Microsoft Entra B2B collaboration, the inviting organization (resource tenant) controls the access requirements for its resources. By default, the resource tenant can require a guest user to complete MFA in that tenant. Microsoft Entra also supports trusting MFA claims from the guest user's home tenant, but this must be configured by the resource tenant administrator.

I recommend the following:

1. Ask the administrator of the inviting organization to check whether a Conditional Access policy is requiring MFA for guest/external users.
2. In the inviting tenant, check: Entra ID > External Identities > Cross-tenant access settings > Organizational settings For your home organization, the administrator should review the inbound trust settings and verify whether “Trust multifactor authentication from Microsoft Entra tenants” is enabled, if their security requirements allow it. When MFA trust is enabled, Microsoft Entra can accept an MFA claim from your home tenant instead of requiring you to register MFA again in the resource tenant.
3. The administrator should also review the Conditional Access policies that apply to guest/external users. In particular, check whether an authentication strength or MFA policy requires an MFA method that your current account/session cannot satisfy. Authentication strength requirements can determine which MFA methods are accepted for external users.
4. If the guest object was created but its invitation redemption is stuck, the inviting administrator can also verify the guest object in: Entra ID > Users They can check whether the guest account corresponding to your #EXT# account exists and whether it is enabled. B2B guest accounts normally appear in the resource tenant as Guest users and use the invited user's external identity for authentication.

I would not recommend resetting the MFA methods on your home account at this stage, since your existing MFA configuration may be working correctly. The error is occurring while the invitation is being redeemed and the resource tenant's security requirements are being evaluated.

For your reference:

• Tutorial: Multifactor authentication for B2B - Microsoft Entra External ID | Microsoft Learn
• Cross-tenant access overview - Microsoft Entra External ID | Microsoft Learn
• How Authentication Strengths Work in a Conditional Access Policy - Microsoft Entra ID | Microsoft Learn
• What is Microsoft Entra B2B collaboration? - Microsoft Entra External ID | Microsoft Learn

If the inviting administrator confirms that MFA trust is configured correctly and the applicable Conditional Access policies are satisfied, but the invitation still fails at the “More information required” step, please provide the following details (with personal information redacted):

• The exact error code shown on the failure page, if available
• Whether the inviting organization uses Conditional Access policies requiring MFA or a specific authentication strength
• Whether MFA trust is enabled for your home organization under Cross-tenant access settings
• Whether the guest account already exists in the inviting tenant
• The sign-in/correlation ID and timestamp from the error page

These details can help determine whether the failure is related to the guest invitation object, MFA registration, Conditional Access, or cross-tenant authentication.