How to fix Error 2203 on Windows Server 2025 / Windows 11

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Microsoft SQL Server 2025 — Error 2203: “%sOnly ‘http://www.w3.org/2001/XMLSchema#decimal?'”

Why This Error Happens

This error occurs when SQL Server 2025 attempts to parse or validate an XML Schema Definition (XSD) and encounters a malformed or unsupported data type reference instead of a proper decimal declaration. It typically stems from corrupted XML schema collections stored in the database, a damaged system catalog entry, or an incompatible XML payload generated by a client application that does not conform to the W3C XMLSchema specification. In some cases, this is triggered by a failed or interrupted schema collection update, leaving a partial reference in sys.xml_schema_collections.

Step-by-Step Resolution Guide

Step 1: Validate the XML Schema Collection

  • Run SELECT name, xml_collection_id FROM sys.xml_schema_collections; to identify the affected schema.
  • Check for truncated or null entries in the xml_schema_namespace definition using SELECT xml_schema_namespace('schema_name', 'collection_name');.
  • Confirm the decimal data type is explicitly declared (e.g., <xs:element name="value" type="xs:decimal"/>) rather than left ambiguous or self-referencing.

Step 2: Rebuild the Corrupted XML Schema Collection

  • Drop the broken collection safely using DROP XML SCHEMA COLLECTION [SchemaName]; (ensure no active dependencies first via sp_depends).
  • Re-import a clean, validated XSD file using CREATE XML SCHEMA COLLECTION [SchemaName] AS N'<xsd file content>';.
  • Store the corrected .xsd file in a trusted path, such as C:\SQLServer\Schemas\, for version control and re-import if needed.

Step 3: Update SQL Server 2025 and Verify Compatibility

  • Open PowerShell as Administrator and run Get-HotFix | Where-Object {$_.Description -like "*SQL Server*"} to confirm the latest Cumulative Update is installed.
  • Apply the latest SQL Server 2025 CU from the Microsoft Update Catalog if missing, as early builds have known XML parser regressions affecting xs:decimal resolution.
  • Restart the SQL Server service via Restart-Service -Name 'MSSQLSERVER' after patching.

Step 4: Reset and Test the Client Connection Layer

  • On Windows Server 2025 / Windows 11, verify the client’s XML serialization library (e.g., .NET System.Xml.Schema) matches the W3C 2001 XMLSchema namespace version expected by SQL Server.
  • Clear any cached connection strings or stale XML payloads in the application layer, then re-test the data submission to SQL Server.

Alternative or Verification Steps

  • Re-run the original query or stored procedure that triggered Error 2203 and confirm no exception is thrown; check sys.messages for Error 2203 recurrence.
  • If the error persists, isolate the issue by testing the XSD independently in a tool like XML Notepad or Visual Studio’s XML Schema Explorer to confirm it’s W3C-compliant before reintroducing it to SQL Server.