Microsoft Entra Connect Sync: Handling LargeObject errors caused by userCertificate attribute

Microsoft Entra ID enforces a maximum limit of 15 certificate values on the userCertificate attribute. If Microsoft Entra Connect exports an object with more than 15 values to Microsoft Entra ID, Microsoft Entra ID returns a LargeObject error with message:

"The provisioned object is too large. Trim the number of attribute values on this object. The operation will be retried in the next synchronization cycle..."

The LargeObject error may be caused by other AD attributes. To confirm it is indeed caused by the userCertificate attribute, you need to verify against the object either in on-premises AD or in the Synchronization Service Manager Metaverse Search.

To obtain the list of objects in your tenant with LargeObject errors, use one of the following methods:

• The Synchronization Service Manager Operations tab displays the list of objects with LargeObject errors if you click the latest Export to Microsoft Entra operation.

Mitigation options

Until the LargeObject error is resolved, other attribute changes to the same object cannot be exported to Microsoft Entra ID. To resolve the error, you can consider the following options:

• Upgrade Microsoft Entra Connect to build 1.1.524.0 or after. In Microsoft Entra Connect build 1.1.524.0, the out-of-box synchronization rules have been updated to not export attributes userCertificate and userSMIMECertificate if the attributes have more than 15 values. For details on how to upgrade Microsoft Entra Connect, refer to article Microsoft Entra Connect: Upgrade from a previous version to the latest.

• Implement an outbound sync rule in Microsoft Entra Connect that exports a null value instead of the actual values for objects with more than 15 certificate values. This option is suitable if you do not require any of the certificate values to be exported to Microsoft Entra ID for objects with more than 15 values. For details on how to implement this sync rule, refer to next section Implementing sync rule to limit export of userCertificate attribute.

• Reduce the number of certificate values on the on-premises AD object (15 or less) by removing values that are no longer in use by your organization. This is suitable if the attribute bloat is caused by expired or unused certificates. You can use the cmdlet Remove-ADSyncToolsExpiredCertificates to help find, backup, and delete expired certificates in your on-premises AD. Before deleting the certificates, it is recommended that you verify with the Public-Key-Infrastructure administrators in your organization.

• Configure Microsoft Entra Connect to exclude the userCertificate attribute from being exported to Microsoft Entra ID. In general, we do not recommend this option since the attribute may be used by Microsoft Online Services to enable specific scenarios. In particular:

  • The userCertificate attribute on the User object is used by Exchange Online and Outlook clients for message signing and encryption. To learn more about this feature, refer to article S/MIME for message signing and encryption.

  • The userCertificate attribute on the Computer object is used by Microsoft Entra ID to allow Windows 10 on-premises domain-joined devices to connect to Microsoft Entra ID. To learn more about this feature, please refer to article Connect domain-joined devices to Microsoft Entra ID for Windows 10 experiences.

Implementing sync rule to limit export of userCertificate attribute

To resolve the LargeObject error caused by the userCertificate attribute, you can implement an outbound sync rule in Microsoft Entra Connect that exports a null value instead of the actual values for objects with more than 15 certificate values. This section describes the steps required to implement the sync rule for User objects. The steps can be adapted for Contact and Computer objects.

The steps can be summarized as:

1. Disable sync scheduler and verify there is no synchronization in progress.
2. Find the existing outbound sync rule for userCertificate attribute.
3. Create the outbound sync rule required.
4. Verify the new sync rule on an existing object with LargeObject error.
5. Apply the new sync rule to remaining objects with LargeObject error.
6. Verify there are no unexpected changes waiting to be exported to Microsoft Entra ID.
7. Export the changes to Microsoft Entra ID.
8. Re-enable sync scheduler.

Step 1: Disable sync scheduler and verify there is no synchronization in progress

Ensure no synchronization takes place while you are in the middle of implementing a new sync rule to avoid unintended changes being exported to Microsoft Entra ID. To disable the built-in sync scheduler:

1. Start PowerShell session on the Microsoft Entra Connect server.

2. Disable scheduled synchronization by running cmdlet: Set-ADSyncScheduler -SyncCycleEnabled $false

1. Start the Synchronization Service Manager by going to START → Synchronization Service.

2. Go to the Operations tab and confirm there is no operation whose status is “in progress.”

Step 2: Find the existing outbound sync rule for userCertificate attribute

There should be an existing sync rule that is enabled and configured to export userCertificate attribute for User objects to Microsoft Entra ID. Locate this sync rule to find out its precedence and scoping filter configuration:

1. Start the Synchronization Rules Editor by going to START → Synchronization Rules Editor.

2. Configure the search filters with the following values:

   Attribute	Value
   Direction	Outbound
   MV Object Type	Person
   Connector	name of your Microsoft Entra connector
   Connector Object Type	user
   MV attribute	userCertificate

3. If you are using OOB (out-of-box) sync rules to Microsoft Entra connector to export userCertificate attribute for User objects, you should get back the “Out to Microsoft Entra ID - User ExchangeOnline” rule.

4. Note down the precedence value of this sync rule.

5. Select the sync rule and click Edit.

6. In the “Edit Reserved Rule Confirmation” pop-up dialog, click No. (Don’t worry, we are not going to make any change to this sync rule).

7. In the edit screen, select the Scoping filter tab.

8. Note down the scoping filter configuration. If you are using the OOB sync rule, there should exactly be one scoping filter group containing two clauses, including:

   Attribute	Operator	Value
   sourceObjectType	EQUAL	User
   cloudMastered	NOTEQUAL	True

Step 3: Create the outbound sync rule required

The new sync rule must have the same scoping filter and higher precedence than the existing sync rule. This ensures that the new sync rule applies to the same set of objects as the existing sync rule and overrides the existing sync rule for the userCertificate attribute. To create the sync rule:

1. In the Synchronization Rules Editor, click the Add new rule button.

2. Under the Description tab, provide the following configuration:

   Attribute	Value	Details
   Name	Provide a name	E.g., “Out to Microsoft Entra ID - Custom override for userCertificate”
   Description	Provide a description	E.g., “If userCertificate attribute has more than 15 values, export NULL.”
   Connected System	Select the Microsoft Entra Connector
   Connected System Object Type	user
   Metaverse Object Type	person
   Link Type	Join
   Precedence	Chose a number between 1 - 99	The number chosen must not be used by any existing sync rule and has a lower value (and therefore, higher precedence) than the existing sync rule.

3. Go to the Scoping filter tab and implement the same scoping filter the existing sync rule is using.

4. Skip the Join rules tab.

5. Go to the Transformations tab to add a new transformation using following configuration:

   Attribute	Value
   Flow Type	Expression
   Target Attribute	userCertificate
   Source Attribute	Use the following expression: IIF(IsNullOrEmpty([userCertificate]), NULL, IIF((Count([userCertificate])> 15),AuthoritativeNull,[userCertificate]))

6. Click the Add button to create the sync rule.

Step 4: Verify the new sync rule on an existing object with LargeObject error

This is to verify that the sync rule created is working correctly on an existing AD object with LargeObject error before you apply it to other objects:

1. Go to the Operations tab in the Synchronization Service Manager.
2. Select the most recent Export to Microsoft Entra operation and click on one of the objects with LargeObject errors.
3. In the Connector Space Object Properties pop-up screen, click on the Preview button.
4. In the Preview pop-up screen, select Full synchronization and click Commit Preview.
5. Close the Preview screen and the Connector Space Object Properties screen.
6. Go to the Connectors tab in the Synchronization Service Manager.
7. Right-click on the Microsoft Entra ID Connector and select Run...
8. In the Run Connector pop-up, select Export step and click OK.
9. Wait for Export to Microsoft Entra ID to complete and confirm there is no more LargeObject error on this specific object.

Step 5: Apply the new sync rule to remaining objects with LargeObject error

Once the sync rule has been added, you need to run a full synchronization step on the AD Connector:

1. Go to the Connectors tab in the Synchronization Service Manager.
2. Right-click on the AD Connector and select Run...
3. In the Run Connector pop-up, select Full Synchronization step and click OK.
4. Wait for the Full Synchronization step to complete.
5. Repeat the above steps for the remaining AD Connectors if you have more than one AD Connectors. Usually, multiple connectors are required if you have multiple on-premises directories.

Step 6: Verify there are no unexpected changes waiting to be exported to Microsoft Entra ID

1. Go to the Connectors tab in the Synchronization Service Manager.
2. Right-click on the Microsoft Entra ID Connector and select Search Connector Space.
3. In the Search Connector Space pop-up:
   1. Set Scope to Pending Export.
   2. Check all 3 checkboxes, including Add, Modify and Delete.
   3. Click Search button to return all objects with changes waiting to be exported to Microsoft Entra ID.
   4. Verify there are no unexpected changes. To examine the changes for a given object, double-click on the object.

Step 7: Export the changes to Microsoft Entra ID

To export the changes to Microsoft Entra ID:

1. Go to the Connectors tab in the Synchronization Service Manager.
2. Right-click on the Microsoft Entra ID Connector and select Run...
3. In the Run Connector pop-up, select Export step and click OK.
4. Wait for Export to Microsoft Entra ID to complete and confirm there are no more LargeObject errors.

Step 8: Re-enable sync scheduler

Now that the issue is resolved, re-enable the built-in sync scheduler:

1. Start PowerShell session.
2. Re-enable scheduled synchronization by running cmdlet: Set-ADSyncScheduler -SyncCycleEnabled $true

Next steps

Learn more about Integrating your on-premises identities with Microsoft Entra ID.