| title | Troubleshoot Fabric Mirrored Databases From SQL Server |
|---|---|
| description | Troubleshooting mirrored databases From SQL Server in Microsoft Fabric. |
| author | WilliamDAssafMSFT |
| ms.author | wiassaf |
| ms.reviewer | ajayj, anagha-todalbagi |
| ms.date | 04/06/2026 |
| ms.topic | troubleshooting |
This article covers troubleshooting steps for mirroring a database in a SQL Server instance.
Learn more from Changes to Fabric capacity.
In addition, note the following causes for SQL Server specifically:
| Cause | Result | Recommended resolution |
|---|---|---|
| Workspace deleted | Mirroring stops automatically and disables the change feed in SQL Server | In case mirroring is still active on the SQL Server, execute the following stored procedure on your SQL Server: exec sp_change_feed_disable_db;. |
| Any other resource errors | Mirroring is disabled | To ensure your compute resources are not impacted and to minimize impact on the SQL Server, mirroring is disabled on any persistent resource errors. |
| "Users can access data stored in OneLake with apps external to Fabric" setting disabled | "Replicator - Tables Cannot Reach Replicating Status" | Enable the Tenant setting Users can access data stored in OneLake with apps external to Fabric. |
The troubleshooting steps and diagnostic queries can be different in SQL Server 2025 and versions before SQL Server 2025.
If you're experiencing mirroring problems in SQL Server 2025, perform the following database level checks using Dynamic Management Views (DMVs) and stored procedures to validate configuration.
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Execute the following query to check if the changes properly flow:
SELECT * FROM sys.dm_change_feed_log_scan_sessions;
-
If the
sys.dm_change_feed_log_scan_sessionsDMV doesn't show any progress on processing incremental changes, execute the following T-SQL query to check if there are any problems reported:SELECT * FROM sys.dm_change_feed_errors;
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If there aren't any issues reported, execute the following stored procedure to review the current configuration of the mirrored SQL Server. Confirm it was properly enabled.
EXEC sp_help_change_feed;
The key columns to look for here are the
table_nameandstate. Any value besides4indicates a potential problem. -
Contact support if troubleshooting is required.
The following extended events session can be used to troubleshoot Fabric Mirroring on your SQL Server 2025 instance. It is recommended only to create this session for troubleshooting or support purposes.
CREATE EVENT SESSION [sqlmirroringxesession] ON SERVER
ADD EVENT sqlserver.synapse_link_addfilesnapshotendentry,
ADD EVENT sqlserver.synapse_link_db_enable,
ADD EVENT sqlserver.synapse_link_end_data_snapshot,
ADD EVENT sqlserver.synapse_link_error,
ADD EVENT sqlserver.synapse_link_info,
ADD EVENT sqlserver.synapse_link_library,
ADD EVENT sqlserver.synapse_link_perf,
ADD EVENT sqlserver.synapse_link_scheduler,
ADD EVENT sqlserver.synapse_link_start_data_snapshot,
ADD EVENT sqlserver.synapse_link_totalsnapshotcount,
ADD EVENT sqlserver.synapse_link_trace
WITH (MAX_MEMORY=4096 KB,EVENT_RETENTION_MODE=ALLOW_SINGLE_EVENT_LOSS,MAX_DISPATCH_LATENCY=30 SECONDS,MAX_EVENT_SIZE=0 KB,MEMORY_PARTITION_MODE=NONE,TRACK_CAUSALITY=OFF,STARTUP_STATE=ON)
GO
ALTER EVENT SESSION [sqlmirroringxesession] ON SERVER
STATE = start;
GOIf the Fabric Mirroring source SQL Server database transaction log is full due to the REPLICATION log reuse wait, consider enabling the autoreseed functionality.
In SQL Server 2025, you can create a resource governor pool to manage and cap the workload of Fabric mirroring on your SQL Server. You can use resource governor to manage Database Engine resource consumption and enforce policies for user workloads. Resource governor lets you reserve or limit various server resources, including the amount of CPU, memory, and physical I/O that user query workloads can use. In this way, you can protect your primary business workloads from pressure from Fabric Mirroring's change feed data collection.
- To get started, see Optimize performance of mirrored databases from SQL Server.
- For more information, see Resource governor.
When creating a new mirrored database SQL Server, the creation might fail with the following error:
Unable to grant required permission to the source server. PowerBI user with prefix undefined not found.
:::image type="content" source="media/troubleshoot/grant-permission-error.png" alt-text="Screenshot of the PowerBI user with prefix undefined not found error.":::
To resolve this:
-
In Fabric portal, cancel the dialog and delete the mirrored database item in the workspace.
-
Open the Azure portal.
- Navigate to Azure Arc (classic) and SQL servers. Then select your Arc-enabled SQL Server instance and select Microsoft Entra ID tab.
- Uncheck the Use a primary managed identity box and select Save.
-
Run the following query in your SQL Server instance repeatedly until it returns no rows:
SELECT * FROM sys.dm_server_managed_identities
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Return to the Azure portal. Go to your Arc-enabled SQL Server instance, and select the Microsoft Entra ID tab.
-
Check Use primary managed identity and select Save.
:::image type="content" source="media/troubleshoot/use-a-primary-managed-identity.png" alt-text="Screenshot of the Use a primary managed identity option in the SQL server instance.":::
-
Run the following query (the same as before) until it returns exactly one row.
SELECT * FROM sys.dm_server_managed_identities
-
In the Fabric portal, setup SQL Server Mirroring to Fabric, which should now succeed without the error.
Change Data Capture (CDC) is used for Fabric Mirroring in versions SQL Server 2025.
- Review Known issues and errors in CDC for common error resolutions.
- Review Administer and monitor CDC for diagnostic queries.
- Review Troubleshoot Fabric mirrored databases.
- Contact support if troubleshooting is required.
For SQL Server versions 2016-2022, mirroring uses CDC.
Error message: Microsoft SQL: Change data capture has not been enabled for source table <schema.table> Specify the name of a table enabled for Change Data Capture. To report on the tables enabled for Change Data Capture, query the <schema_table> column in the <schema.table> catalog view.
This error occurs if CDC is not already enabled or mirroring does not have sufficient permissions to enable CDC.
- Check if CDC is enabled in the database.
- Follow steps in Enable and disable CDC to enable CDC for the table you want to mirror.
Error message: Microsoft SQL: The database <dbName> is not enabled for Change Data Capture. Ensure that the correct database <dbName> is set and retry the operation. To report on the databases enabled for Change Data Capture, query the <schema_table> column in the <schema.table> catalog view.
This error occurs if CDC is not already enabled, or mirroring does not have sufficient permissions to enable CDC. See Enable and disable CDC to enable CDC for the database you want to mirror.
Error message: Microsoft SQL: The parameter @supports_net_changes is set to <num>, but the source table does not have a primary key defined and no alternate unique index has been specified.
Fabric Mirroring requires primary key for a table to be mirrored. Ensure that the table being mirrored has a primary key.
Fabric cannot connect to the on-premises data gateway (OPDG) endpoint due to a gateway connectivity issue. To troubleshoot, see Service gateway troubleshooting.
The credentials specified in the connection failed to authenticate in SQL Server. User logins can fail for many reasons, such as invalid credentials, password expiration, or insufficient permissions.
- Check if the login or password is correct.
- Ensure that the login specified has permissions in the database being mirrored.
The credentials specified in the connection failed to authenticate in SQL Server. User logins can fail for many reasons, such as invalid credentials, password expiration, or insufficient permissions.
- Check if the login or password is correct.
- Ensure that the login specified has permissions in the database being mirrored.
Error message: Microsoft SQL: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (Provider: Named Pipes Provider, error: <num> - Could not open a connection to SQL Server)
This error occurs if on-premises data gateway (OPDG) cannot connect to the SQL Server instance. Follow the steps in A network-related or instance-specific error occurred while establishing a connection to SQL Server to troubleshoot and resolve the SQL Server connectivity issue.
For SQL Server 2016-20222, Fabric Mirroring uses SQL Server Agent CDC jobs to track changes in the source tables. This error occurs if SQL Server Agent is not running, resulting in the changes on the sources exceeding the default retention interval. Ensure the SQL Server Agent is running and set to automatically start when the server is restarted.
Error message: Table <schema.table> definition has changed since CDC was enabled. Please re-enable CDC (EXEC ...)
This error occurs if source schema for the mirrored table was changed after CDC was enabled. This results in the mirrored table schema not matching the source table schema. Disable and re-enable CDC on the impacted tables. See Enable and disable CDC.