B2B guest invitations blocked tenant-wide — "Invitations are blocked for this directory due to suspicious activity" — request review and removal of block

**
Hello,

I am the Global Administrator of the tenant below. All B2B guest invitations in our tenant are failing tenant-wide, and Microsoft Graph returns an explicit fraud-hold error asking us to contact support. I am requesting an investigation and removal of this invitation block.

Tenant details

• Tenant domain: rpavault9.onmicrosoft.com
• Tenant ID: 705299f7-804d-40a1-938c-55dbdc1a894a
• Reporter: tenant Global Administrator

Exact error from Microsoft Graph (POST https://graph.microsoft.com/v1.0/invitations)

{

"error": {

"code": "Forbidden",

"message": "Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.",

"innerError": {

"request-id": "5580c1b6-a5b5-4c31-aade-519cefc0a59c",

"date": "2026-07-26T14:16:06",

"client-request-id": "f4a029e6-8422-f554-9f95-d38043907fca"

}

}

}

How the issue appears in other surfaces

When inviting via the Entra admin center or sharing from SharePoint/OneDrive, the same underlying block surfaces as a misleading error:

Error from Entra B2B: At least one invitation failed. Error: ReadResponseFailure, message: Cannot access a disposed object. Object name: 'System.Net.HttpWebResponse'.

What I have already verified (all correct)

• External collaboration settings: guest invites are allowed; no domain allow/deny list blocking the invited addresses
• Cross-tenant access settings: default inbound B2B collaboration is allowed
• No stale/conflicting guest object for the invited email (checked All users and Deleted users)
• My account holds the Global Administrator role
• Reproduced with Security Defaults temporarily disabled — same error, so no tenant policy on our side is causing this
• Reproduced via three independent paths: Entra portal "Invite external user", SharePoint/OneDrive sharing, and the raw Graph API (error above)

Context / legitimate use

We are a small business (an IT training and services company) inviting a small number of known external collaborators to work on SharePoint documents. These are legitimate, low-volume business invitations. The repeated invitation attempts in our logs today were troubleshooting retries of this same failure, not bulk sending.

Request

Please review the automated fraud/abuse hold on B2B invitations for this tenant and remove it. The request-id and client-request-id above should let the team locate the block server-side. I'm happy to provide any further verification of the tenant or my identity through a private/official channel.

Impact: External collaborators are completely blocked from accessing shared resources; this is blocking active business work.

Thank you.

Extra More info
Environment**

Product: Microsoft Entra ID — External Identities (B2B collaboration)

Tenant: RPAVAULT (rpavault9.onmicrosoft.com)

Portal: Microsoft Entra admin center → External Identities → External collaboration settings

What I’m trying to do Invite an external user as a B2B guest to my tenant.

What happens The guest invitation fails. The portal returns a ReadResponseFailure error, followed by a “Cannot access a disposed object” message. The invite does not complete and the guest user is not created.

Current configuration (External collaboration settings)

Guest invite restrictions: [state which option is selected — e.g. “Anyone in the organization can invite” vs “Only specific admin roles”]

Guest user access restrictions: [which option is selected]

Collaboration restrictions: [Allow any domain / Deny specific domains / Allow only specific domains]

Cross-tenant access settings: [any inbound/outbound restrictions configured?]

Steps to reproduce

1. Go to External Identities → External collaboration settings (or Users → New guest user).
2. Enter the external email address and send the invitation.
3. Error appears: ReadResponseFailure → “Cannot access a disposed object”.

What I’ve already tried

• [e.g. different browser, cleared cache, tried a different admin account, retried invite]Environment
• Product: Microsoft Entra ID — External Identities (B2B collaboration)
• Tenant: RPAVAULT (rpavault9.onmicrosoft.com)
• Portal: Microsoft Entra admin center → External Identities → External collaboration settings What I’m trying to do Invite an external user as a B2B guest to my tenant. What happens The guest invitation fails. The portal returns a ReadResponseFailure error, followed by a “Cannot access a disposed object” message. The invite does not complete and the guest user is not created. Current configuration (External collaboration settings)
• Guest invite restrictions: Anyone in the organization can invite
• Guest user access restrictions: Enabled
• Collaboration restrictions: Allow any domain Steps to reproduce

1. Go to External Identities → External collaboration settings (or Users → New guest user).
2. Enter the external email address and send the invitation.
3. Error appears: ReadResponseFailure → “Cannot access a disposed object”.

Details to add

• Exact email domain being invited: gmail
• Full error text / correlation ID: added in attachment
• When it started / whether it ever worked: No, this is a new tenant account
• Browser and whether it reproduces in incognito: same error in incognito What I’ve already tried
  • tried different browsera, cleared cache, tried a different admin account, retried invite

        {
            "error": {
                "code": "Forbidden",
                "message": "Invitations are blocked for this directory due to suspicious activity. Please contact Microsoft support for help.",
                "innerError": {
                    "request-id": "5580c1b6-a5b5-4c31-aade-519cefc0a59c",
                    "date": "2026-07-26T14:16:06",
                    "client-request-id": "f4a029e6-8422-f554-9f95-d38043907fca"
                }
            }
        }