Unable to add or invite external users

Question

I am a Global Administrator and I am unable to invite any new external (B2B) users. Every invitation attempt fails with the error:

“User invitation failed – Insufficient privileges to complete the operation.”

This happens for all external domains, including consumer domains. Guest access settings, cross‑tenant access settings, identity providers, and allow/deny lists are all correctly configured.

To investigate, I ran the Microsoft Graph PowerShell command:

Code Get-MgPolicyAuthorizationPolicy This returned no objects at all, which indicates that the Authorization Policy object is missing from the tenant. This prevents new B2B guest invitations even for Global Administrators.

Guest user invitations are blocked at the tenant level. I am a Global Admin in a voluntary organisation on a one month trial leading to paid subscription. Invitations were working successfully up to 15 guests, then began failing with 'Insufficient privileges to complete the operation.' All collaboration settings are configured correctly. This appears to be a tenant-level block triggered by Microsoft's anomaly detection. Please unblock B2B invitations for this tenant.

I raised an Azure support ticket on 10th March and have had no response despite chasing. Please help @Sridevi Machavarapu (you asked me to tag you when I commented on a similar question - I was hoping support ticket would resolve but back here now), looking forward to hearing from you.

Answer 1

The error “User invitation failed – Insufficient privileges to complete the operation” when inviting any B2B guest, even as Global Administrator, is consistent with a tenant‑level restriction rather than a per‑user permission or configuration issue.

From the provided information, all standard B2B controls are already correctly configured:

• External collaboration settings (who can invite guests, guest access level)
• Cross‑tenant access settings
• Allow/deny domain lists
• Identity providers

In a normal, healthy tenant, a Global Administrator or User Administrator can invite external users as B2B guests via the Microsoft Entra admin center or PowerShell, as described in the standard flow:

1. Sign in as at least a User Administrator.
2. Go to Entra ID > Users > New user > Invite external user.
3. Enter the guest’s email and send the invitation.

If this fails for all domains with “Insufficient privileges” despite Global Administrator role and correct collaboration settings, and Get-MgPolicyAuthorizationPolicy returns no object, this indicates a tenant‑side problem that cannot be fixed from the portal or by role changes alone.

Given that:

• Guest invitations worked initially and then stopped after a small number of guests.
• The tenant is on a trial subscription.
• The behavior matches a hard block at the tenant level (for example, anomaly‑based restriction or a missing/invalid authorization policy object).

The only viable remediation is through Microsoft support, because:

• Creation or repair of the tenant’s Authorization Policy object is not exposed through Entra admin center or standard Graph operations for customers.
• Trial tenants and anomaly‑based blocks are handled by internal support processes.

Recommended next steps:

1. Continue to work through the existing Azure/Microsoft 365 support ticket, explicitly referencing that Get-MgPolicyAuthorizationPolicy returns no object and that B2B invitations fail for Global Administrator with “Insufficient privileges to complete the operation.”
2. If the existing ticket remains unanswered, open a new support request from the tenant that still has portal access (for example, via https://entra.microsoft.com or https://portal.azure.com) and attach the failing invitation screenshots and the Get-MgPolicyAuthorizationPolicy output.
3. Ask support specifically to:
   • Verify and, if necessary, recreate/repair the tenant’s Authorization Policy object.
   • Confirm whether any anomaly‑based or abuse‑prevention block has been applied to B2B invitations in this tenant and remove it if appropriate.

There is no configuration‑side workaround in Entra ID or PowerShell documented in the provided material that would bypass a missing Authorization Policy object or a tenant‑level B2B block. Resolution depends on Microsoft support intervention at the tenant level.

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References:

• Configure external collaboration settings for B2B in Microsoft Entra External ID
• Overview: B2B collaboration with external guests for your workforce
• Add and manage B2B collaboration users in the Microsoft Entra admin center
• Invite users with Microsoft Entra B2B collaboration
• Troubleshoot common issues with Microsoft Entra B2B collaboration