How to fix Error 6907 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 6907 – “Namespace URI too long”

Why This Error Happens

Error 6907 occurs when SQL Server’s XML parser encounters a namespace URI that exceeds the internal length limit enforced by the XML data type engine. This is typically caused by malformed or auto-generated XML documents (often from third-party integrations or BI tools) that embed excessively long or dynamically concatenated namespace strings. In some cases, it also surfaces due to corrupted XML schema collections (XSC) registered in the database that contain bloated or duplicated namespace declarations.

Step-by-Step Resolution Guide

Step 1: Identify the Offending XML Source

  • Capture the exact query or stored procedure throwing Error 6907 using SQL Server Profiler or Extended Events on Windows Server 2025.
  • Check the application layer (SSIS packages, Power BI connectors, or REST API payloads) for XML inputs with concatenated or auto-generated namespace URIs.
  • Run the following to inspect recent XML-related errors:
SELECT * FROM sys.messages WHERE message_id = 6907;

Step 2: Validate and Trim the Namespace URI

  • Open the source XML document and manually inspect the xmlns attributes for unusually long strings (typically over 4,000 characters).
  • Shorten or standardize the namespace URI to a conventional format, such as http://schemas.yourcompany.com/v1.
  • If the XML is generated programmatically (e.g., via C# XmlWriter or Python lxml), audit the code for string concatenation loops that may be appending data unintentionally into the namespace field.

Step 3: Repair or Rebuild XML Schema Collections

  • If the error originates from a registered XML Schema Collection (XSC), drop and recreate it with corrected namespace definitions:
DROP XML SCHEMA COLLECTION dbo.YourSchemaCollection;
GO
CREATE XML SCHEMA COLLECTION dbo.YourSchemaCollection AS N'<schema>...corrected XML...</schema>';
GO
  • Ensure the new schema file is UTF-8 encoded and validated using an external tool (like xmllint or Visual Studio’s XML Schema Explorer) before re-import.

Step 4: Update SQL Server 2025 Cumulative Updates

  • Navigate to Microsoft Update Catalog and verify you are running the latest Cumulative Update (CU) for SQL Server 2025, as early builds had a known buffer-handling bug related to the %.*ls string formatter in XML parsing.
  • Apply the update via Setup.exe /Action=Patch /AcceptSQLServerLicenseTerms /Quiet on the Windows Server 2025 host.
  • Restart the SQL Server service (MSSQLSERVER) after patching.

Alternative or Verification Steps

  • Verification: Re-run the original query or XML import process; monitor the SQL Server Error Log (C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG) to confirm Error 6907 no longer appears.
  • Alternative Fix: If the namespace length cannot be reduced at the source, convert the field to NVARCHAR(MAX) instead of native XML type for storage, and handle parsing/validation at the application layer using a library with configurable buffer limits (e.g., .NET’s XmlReaderSettings).