Microsoft 365 Error Codes

How to Fix Object Reference Errors for Microsoft 365 Distribution Lists

Tauseeq Magsi Oct 9, 2026 869 views

Question details

Users encounter an object reference error when attempting to add approved senders or change moderator approval for distribution lists.

How to Fix Object Reference Errors for Microsoft 365 Distribution Lists

Product: Microsoft 365 Admin Center
Device & OS: not provided
Scenario: Administrators are trying to update moderation settings and approved senders for distribution lists in the Microsoft 365 admin center under the Teams and groups section.
Observed behavior: The system throws an object reference error when attempting to save the changes, particularly affecting user accounts synchronized from on-premises Active Directory.

Before you start

Verify whether your organization's user accounts and distribution lists are meant to be managed natively in Microsoft 365 or through an on-premises Exchange server.

Solution 1Recommended

Verify Directory Synchronization and Collect Diagnostic Data

Confirm that the affected distribution lists and user accounts have successfully synchronized to Microsoft 365 and gather necessary details to escalate the issue.

Because the affected accounts were created in an on-premises Active Directory and synchronized to Microsoft 365, object reference errors typically occur when specific Exchange recipient properties fail to sync properly. The issue must be investigated at the synchronization and backend level.

Check Microsoft 365 Admin Center

Navigate to the Microsoft 365 admin center and access the 'Teams and groups' section to inspect the properties of the affected distribution lists.

Verify Synchronization Status

Check the Active Directory sync status in your admin dashboard to ensure the user mailboxes and distribution groups are fully synchronized without any pending errors.

Collect Directory Details

Take clear screenshots of the object reference error message and document the affected directory details, including user UPNs and distribution list names.

Open a Support Request

Submit the collected screenshots and synchronization logs through a Microsoft 365 support request, as backend object reference errors often require Microsoft intervention to resolve.

Verify Directory Synchronization and Collect Diagnostic Data

On-Premises Management Restriction: If you operate in an Exchange hybrid environment, you may be required to modify distribution group attributes on the on-premises Exchange server rather than directly in the Microsoft 365 admin center.

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Frequently Asked Questions

Why am I getting an object reference error in the Microsoft 365 admin center?

This error typically occurs when an expected attribute or property on a synchronized user or group object is missing, malformed, or out of sync between your on-premises Active Directory and Microsoft 365.

Should I manage synchronized distribution lists in Microsoft 365 or on-premises?

If your organization uses Azure AD Connect with an Exchange Hybrid environment, certain distribution list properties and moderation settings must be managed from the on-premises Exchange admin center and then synchronized to Microsoft 365.

Can I fix the object reference error by forcing an Active Directory sync?

Sometimes forcing a delta sync using Azure AD Connect can resolve temporary attribute mismatches. However, if backend data corruption exists, Microsoft 365 support will need to correct the broken object references.

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