Home data integration delta import errors troubleshooting

Troubleshooting Delta Import Error: Resolving Size Limit Exceeded (Code 0x4)

Updated: • 0 • min read
Table of Contents

Troubleshooting Delta Import Error: Resolving Size Limit Exceeded (Code 0x4)

Microsoft Entra Connect plays a crucial role in synchronizing identities between your on-premises Active Directory and Microsoft Entra ID (formerly Azure Active Directory). This synchronization process involves several steps, including delta imports, which are designed to efficiently bring in only the changes that have occurred since the last synchronization cycle. However, administrators may sometimes encounter errors during the delta import phase, specifically the “Size Limit Exceeded - Error Code 0x4”. This error indicates that a query performed by Microsoft Entra Connect against your on-premises Active Directory has returned more results than the configured limit allows. Understanding the cause and available solutions is key to resolving this interruption in synchronization.

Understanding the Synchronization Process

To appreciate where the “Size Limit Exceeded” error fits in, it’s helpful to briefly outline the Microsoft Entra Connect synchronization cycle. A typical cycle involves several distinct steps performed sequentially by the synchronization engine. These steps include:

  1. Import: Data is read from connected data sources, such as your on-premises Active Directory (AD CS) and Microsoft Entra ID. This step can be either a “Full Import” or a “Delta Import.” A delta import is the standard operation during regular synchronization cycles, designed to pull only changes (creations, modifications, deletions) since the last successful import.
  2. Synchronization: Changes imported from connected data sources are processed against the metaverse, the central repository of synchronized identity information within Microsoft Entra Connect. Rules defined in the synchronization engine determine how objects are joined, projected, and provisioned between the connected systems.
  3. Export: Changes processed in the synchronization step are written back to the connected data sources, such as provisioning new users in Microsoft Entra ID or writing attributes back to Active Directory (if configured for writeback).

The “Size Limit Exceeded” error specifically occurs during the Delta Import step from the on-premises Active Directory connector. This phase relies on queries (specifically, LDAP queries) against your domain controllers to retrieve the list of changes that need to be processed.

Here is a simplified conceptual diagram of the process:

mermaid graph TD A[On-Premises Active Directory] -->|Delta Import Query| B(Microsoft Entra Connect Sync Engine); B --> C(Metaverse); C --> D[Microsoft Entra ID]; D -->|Export| B; C -->|Export| A;
Conceptual flow showing Delta Import from AD to the Sync Engine.

Symptoms

The most direct indication of the “Size Limit Exceeded” error will be visible in the Synchronization Service Manager application, which is the primary tool for monitoring and managing Microsoft Entra Connect synchronization operations.

In the Synchronization Service Manager user interface, navigate to the “Operations” tab. Here, you will see a history of all synchronization runs. When the error occurs, the “Delta Import” step for your on-premises Active Directory connector will show a failure status. The specific status reported is typically “stopped-connectivity”. Clicking on the failed run entry will open a detailed dialog box. Within this dialog, the “Connection Log” section will display the specific error details. You will see entries indicating a “dropped-connection” status, the prominent error message “Size Limit Exceeded”, and the specific error code 0x4.

Beyond the Synchronization Service Manager GUI, this error is also logged in the Windows Application event log on the server running Microsoft Entra Connect. An error event with Event ID 6050 is typically recorded. The event details will confirm the failure of the management agent (connector) associated with your on-premises Active Directory during the “Delta Import” run profile due to connectivity issues, providing additional context that points towards the underlying problem.

Here is an example of the event log entry:

Log Name:      Application
Source:        ADSync
Date:          5/12/2023 7:34:38 AM
Event ID:      6050
Task Category: Management Agent Run Profile
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      AADConnect.Contoso.com
Description:
The management agent "Contoso.com" failed on run profile "Delta Import" because of connectivity issues.

Additional Information
Discovery Errors       : "0"
Synchronization Errors : "0"
Metaverse Retry Errors : "0"
Export Errors          : "0"
Warnings               : "0"

User Action
View the management agent run history for details.

This event log entry confirms the connector failure during the delta import, aligning with the information seen in the Synchronization Service Manager and helping to diagnose the specific phase and connector affected.

Cause

The root cause of the “Size Limit Exceeded - Error Code 0x4” error during the delta import from Active Directory is directly related to a default security setting within the Active Directory Lightweight Directory Access Protocol (LDAP) service. By default, Active Directory is configured to limit the number of records that can be returned by a single LDAP query to a maximum of 1,000. This limit is controlled by the MaxPageSize LDAP policy setting.

This default limit of 1,000 records is a security measure designed to prevent excessive resource consumption on domain controllers. It helps protect against potential denial-of-service (DoS) or distributed denial-of-service (DDoS) attacks that could be launched by repeatedly issuing large, resource-intensive LDAP queries. By limiting the size of the result set, the load on the domain controller is kept within manageable bounds, preserving its responsiveness and stability.

Under normal circumstances, a standard delta import query from Microsoft Entra Connect would not exceed this limit. Delta imports are designed to retrieve only the changes that have occurred since the last successful synchronization cycle. Typically, the number of objects changed within a few minutes or hours is well below the 1,000-record threshold.

However, certain events can cause an unusually large number of changes to occur simultaneously, leading the delta import query to attempt to retrieve a result set larger than 1,000 records. A common scenario that triggers this specific error is the bulk restoration of objects from the Active Directory Recycle Bin. When numerous user accounts, groups, or other objects are restored concurrently, Active Directory registers these restorations as changes. The delta import query, looking for all changes, then attempts to pull information about all these newly restored objects in one go. If the total count of changed objects (including restorations and any other concurrent modifications) exceeds 1,000, the domain controller will enforce the MaxPageSize limit and return the “Size Limit Exceeded” error to Microsoft Entra Connect, causing the delta import step to fail. Other scenarios could involve mass script-based modifications or creations of users/groups that inadvertently happen between delta sync cycles.

Solution 1: Run a Full Import on the AD DS Connector

One of the simplest and often most effective ways to resolve the “Size Limit Exceeded” error is to temporarily bypass the standard delta import process by running a full import on the affected Active Directory Domain Services (AD DS) connector. A full import differs from a delta import in how it operates. Instead of querying for changes based on timestamps or change tracking mechanisms, a full import reads all selected objects from the connected directory. While this is generally less efficient than a delta import for routine cycles, it can sometimes process large sets of changes differently or consolidate the result set in a way that avoids triggering the MaxPageSize limit imposed on the delta change tracking query itself.

Performing a full import on the AD connector essentially forces Microsoft Entra Connect to re-evaluate the entire scope of objects it is configured to synchronize from Active Directory. This operation is resource-intensive and can take significantly longer than a delta import, especially in large environments. However, it can effectively clear the backlog of changes that caused the delta import to fail due to the size limit.

Here are the steps to manually initiate a full import using the Synchronization Service Manager:

  1. Open the Synchronization Service Manager application. You can typically find this by searching for “Synchronization Service” or “Synchronization Service Manager” in the Windows Start menu.
  2. In the Synchronization Service Manager window, navigate to the “Operations” tab. Locate the recent synchronization run history. Identify the row corresponding to the Delta Import step for your on-premises AD Connector that shows the “stopped-connectivity” status and is associated with the “Size Limit Exceeded” error. Note the name of the connector.
  3. Switch to the “Connectors” tab. Find the specific Active Directory connector identified in the previous step.
  4. With the AD connector selected, you need to initiate a run profile manually. Right-click on the connector name, or select the connector and press Ctrl+F5. This action will open the “Run Connector” dialog box.
  5. In the “Run Connector” dialog box, you will see a list of available run profiles for that connector. Select the Full Import run profile from the list.
  6. Click OK to start the full import operation.

The Synchronization Service Manager will now execute a full import run for the selected AD connector. Monitor the “Operations” tab to track its progress. This operation may take a considerable amount of time depending on the size of your Active Directory environment and the number of objects being imported. Once the Full Import run profile completes successfully (it should show a “success” status, potentially with some warnings, but crucially not the “stopped-connectivity” or “Size Limit Exceeded” error), the backlog of changes should be resolved.

After the full import has finished, you should resume normal synchronization operations. This is done by initiating a regular synchronization cycle, which will start with a delta import followed by synchronization and export steps. The recommended way to do this is using the PowerShell cmdlet Start-ADSyncSyncCycle.

Open a PowerShell console on the Microsoft Entra Connect server and run the following command:

Start-ADSyncSyncCycle

This cmdlet instructs the Microsoft Entra Connect scheduler to begin a new synchronization cycle immediately. The scheduler, which by default runs every 30 minutes, will pick up this manual trigger and initiate the configured run profiles, starting with delta imports. Because the full import has already processed the bulk changes that caused the previous failure, the subsequent delta import should now successfully retrieve only the new changes that have occurred since the full import finished, well within the standard size limits.

This approach is often the preferred first step because it avoids modifying critical Active Directory configuration settings and leverages the built-in capabilities of Microsoft Entra Connect.

Solution 2: Temporarily Increase the Record Limit

If running a full import is not feasible (e.g., due to time constraints, impact on domain controllers, or other operational reasons) or if the issue persists after a full import, an alternative solution involves temporarily adjusting the default LDAP MaxPageSize limit in Active Directory. This allows the problematic delta import query to return a larger number of results, accommodating the spike in changes that triggered the “Size Limit Exceeded” error.

Important Considerations and Warnings:

Modifying Active Directory LDAP policies, especially MaxPageSize, is a significant configuration change that affects the behavior of your domain controllers globally. While necessary for this specific troubleshooting scenario, it’s crucial to understand the implications:

  • Increasing MaxPageSize can potentially increase the load on your domain controllers during LDAP queries. If set excessively high or left permanently changed, it could make domain controllers more vulnerable to resource exhaustion from malicious or poorly optimized queries.
  • This change should be considered temporary. The recommended practice is to increase MaxPageSize only long enough for the problematic delta import to complete successfully, and then immediately restore it to its default value of 1,000.
  • Follow the steps precisely. Incorrectly modifying LDAP policies can lead to unexpected behavior or issues within your Active Directory environment.

The tool used to view and modify Active Directory LDAP policies is ntdsutil.exe. This command-line utility is a powerful tool for managing various aspects of Active Directory, including metadata cleanup, file management, and LDAP policy administration.

Here are the steps to temporarily increase the MaxPageSize using ntdsutil:

  1. Log on to a domain controller in the domain exhibiting the issue or a server with the Active Directory Domain Services role administration tools installed.
  2. Open a Command Prompt as an administrator. Right-click the Command Prompt shortcut and select “Run as administrator.”
  3. At the command prompt, type ntdsutil and press Enter to enter the ntdsutil interactive console.
  4. Within the ntdsutil console, type ldap policies and press Enter to enter the LDAP policies management mode.
  5. Now, you can manage the policies. To see the current settings, type show values and press Enter. This will display the current effective LDAP policy settings, including MaxPageSize, MaxQueryDuration, MaxConnections, etc. Note down the current value of MaxPageSize. It should be 1000 by default.
  6. To change the maximum page size, type the following command, replacing <new-maximum-page-size-value> with a value large enough to accommodate the expected number of changes that caused the error. For example, if you restored an OU with 5,000 users, setting it to 5000 or slightly higher would be appropriate. A safe temporary value could be 10000 or 20000 if you are unsure of the exact count, but avoid excessively large numbers unless absolutely necessary and understood. The command is: set MaxPageSize to <new-maximum-page-size-value>
    For example, to set it to 5000:
    set MaxPageSize to 5000

    Press Enter.
  7. After setting the new value, you must commit the changes to make them effective. Type commit changes and press Enter. You should receive a confirmation message indicating that the changes were successfully written.
  8. To exit the ntdsutil LDAP policies mode, type quit and press Enter.
  9. To exit the main ntdsutil console, type quit again and press Enter.

The change to MaxPageSize is generally immediate or propagates quickly across domain controllers within the site.

After successfully increasing the MaxPageSize, return to the Microsoft Entra Connect server. Open a PowerShell console and run the Start-ADSyncSyncCycle cmdlet to initiate a normal synchronization cycle:

Start-ADSyncSyncCycle

This will trigger a delta import. With the increased MaxPageSize on the domain controllers, the delta import query from Microsoft Entra Connect should now be able to retrieve the complete list of changes that previously exceeded the 1,000-record limit. Monitor the Synchronization Service Manager’s “Operations” tab. The delta import step for the AD connector should now complete successfully (status “success”).

Once the synchronization cycle that includes the successful delta import is complete (it might take one full cycle including synchronization and export), it is critically important to restore the MaxPageSize setting back to its original default value of 1,000. Repeat steps 1-9 of the ntdsutil procedure described above, but in step 6, set the MaxPageSize value back to 1000.

set MaxPageSize to 1000

Then, remember to commit changes and quit out of ntdsutil.

This temporary change and subsequent restoration minimize the exposure window during which your domain controllers operate with a less restrictive query limit.

Comparing the Solutions

Both solutions aim to allow Microsoft Entra Connect’s delta import to process a large volume of changes. Here’s a brief comparison:

Feature Solution 1: Full Import Solution 2: Temporarily Increase MaxPageSize
Complexity Simple GUI steps in Sync Service Mgr Requires administrative Command Prompt access and using ntdsutil
Impact on AD Config None Modifies a critical AD policy (temporary)
Sync Time Can be very long (reads all objects) Delta import can be faster after the change
Risk Low risk to AD infrastructure Potential moderate risk if not restored quickly
When to Use Generally preferred first step; simplest approach When Full Import is not feasible or doesn’t resolve the issue

Generally, attempting a Full Import (Solution 1) first is recommended due to its simplicity and lower risk. If that fails or is impractical, Temporarily Increasing MaxPageSize (Solution 2) is the targeted approach to allow the specific problematic delta query to succeed, followed by restoring the default AD setting.

Monitoring After Resolution

After implementing either solution, it is essential to monitor the subsequent synchronization cycles using the Synchronization Service Manager. Ensure that the Delta Import step for your AD connector consistently completes with a “success” status during routine scheduled runs. Also, check the Application Event Log for any recurring Event ID 6050 errors related to the AD connector. Successful synchronization cycles will indicate that the “Size Limit Exceeded” issue has been resolved.

Continued monitoring is always a good practice for any identity synchronization solution to catch potential issues early. If the error recurs frequently without apparent cause (like large bulk restores), it might indicate an underlying issue with the Active Directory environment or the synchronization scope that needs further investigation.

Addressing the “Size Limit Exceeded” error promptly is vital to ensure that your on-premises Active Directory and Microsoft Entra ID remain synchronized, maintaining a consistent and accurate representation of your user identities in the cloud.

Have you encountered this “Size Limit Exceeded” error during your Microsoft Entra Connect operations? Which solution worked best for you, or did you find another approach? Share your experiences and thoughts in the comments below!

Post a Comment