How to fix Error 7325 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: Error 7325 – CLR Type Columns Not Allowed in Distributed Queries

Why This Error Happens

This error occurs because SQL Server’s distributed query engine cannot serialize CLR (Common Language Runtime) data types—such as hierarchyid, geometry, geography, or custom CLR user-defined types—across a linked server connection. The OLE DB provider used for the remote connection lacks the metadata translation layer required to marshal these complex types over the distributed query protocol. This is a design limitation rather than a configuration defect, meaning standard four-part naming queries (Server.Database.Schema.Object) against tables containing these columns will always fail unless rewritten as pass-through queries using OPENQUERY.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Column and Object

  • Run sp_help 'YourTableName' on the remote server to locate columns using CLR-based types (hierarchyid, geometry, geography, or custom assemblies).
  • Note the exact remote object name referenced in the error message (the %ls placeholder).
  • Confirm the query is using four-part naming syntax, e.g., SELECT * FROM LinkedServer.DB.dbo.TableName.

Step 2: Rewrite the Query Using OPENQUERY (Pass-Through Query)

  • Replace the standard distributed query with an OPENQUERY statement, which forces execution on the remote server and returns only the result set:
SELECT * 
FROM OPENQUERY(LinkedServer, 'SELECT ID, Name, GeoColumn.ToString() AS GeoColumn FROM dbo.TableName');
  • If the CLR column itself is not needed in the output, explicitly exclude it from the inner SELECT list rather than using SELECT *.
  • For spatial types specifically, convert them to a string or binary representation inline (e.g., .ToString() or .STAsText()) before they cross the linked server boundary.

Step 3: Verify Linked Server Provider Settings

  • Open SQL Server Management Studio (SSMS) and navigate to Server Objects > Linked Servers > [Your Linked Server] > Properties.
  • Under Provider Options, ensure “Nested Queries” and “Allow InProcess” are enabled for the OLE DB provider (relevant for SQLNCLI11 or MSOLEDBSQL).
  • Run the following to confirm provider settings via T-SQL:
EXEC sp_linkedserver_catalog 'LinkedServer';

Step 4: Update CLR Assembly and Driver Versions

  • On Windows Server 2025/Windows 11, confirm the Microsoft OLE DB Driver for SQL Server (MSOLEDBSQL) is updated to the latest version compatible with SQL Server 2025.
  • Check installed version via PowerShell:
Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\MSOLEDBSQL" | Select-Object Version
  • Reinstall or update the driver from the official Microsoft Download Center if the version predates SQL Server 2025 compatibility updates.

Alternative or Verification Steps

  • To verify the fix, re-run the rewritten OPENQUERY statement and confirm it returns data without throwing Error 7325.
  • As an alternative, if frequent access is needed, create a view on the remote server that casts the CLR column to a standard SQL type (e.g., NVARCHAR(MAX)), then query that view directly through the linked server instead of the base table.