How to fix Error 9315 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 9315

Why This Error Happens

Error 9315 occurs when an XQuery expression in SQL Server attempts to use a dynamic or variable value (such as a column reference, parameter, or function result) as the name for a computed element or attribute constructor. SQL Server’s XML/XQuery engine mandates that the name portion of these constructors be resolved at compile time, meaning only literal, constant string values are permitted. This typically surfaces in applications performing XML data transformations after an upgrade or migration to SQL Server 2025, where legacy XQuery syntax may not have been validated against stricter parsing rules.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Query

  • Open SQL Server Management Studio (SSMS) and check the Activity Monitor or SQL Server Logs (C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\) to find the exact query triggering Error 9315.
  • Look specifically for .query(), .value(), or .nodes() methods combined with element {} or attribute {} constructors in the T-SQL code.
  • Use SELECT * FROM sys.dm_exec_query_stats cross-referenced with sys.dm_exec_sql_text to pinpoint the exact batch if the error occurs in a stored procedure.

Step 2: Refactor the XQuery Constructor Syntax

  • Locate the dynamic variable being used inside the curly braces, for example: element {@DynamicName} { ... }.
  • Since SQL Server requires a constant, you cannot pass a variable directly into the name slot. Refactor the logic to use a CASE statement that maps variables to hardcoded string literals, or restructure the query to use FOR XML PATH instead of native XQuery constructors if the element names must be dynamic.
  • Example fix: Replace element {@var}{} with a static definition like element Root {} if the name is static, or pivot to generating the XML string via concatenation if dynamic names are strictly required.

Step 3: Update Compatibility Level and Rebuild Execution Plans

  • Since this is running on SQL Server 2025, ensure the database compatibility level is correctly set to support the newer XQuery parser (should be 170 or higher).
  • Run the following command to check and set the level:
ALTER DATABASE [YourDatabaseName] SET COMPATIBILITY_LEVEL = 170;
  • Clear the procedure cache to ensure the old, erroring execution plan isn’t being reused: DBCC FREEPROCCACHE;.

Step 4: Validate XML Schema Collections

  • If the query is binding to an XML Schema Collection (XSD), verify that the schema hasn’t been corrupted during the Windows Server 2025 migration.
  • Check schema integrity using: SELECT * FROM sys.xml_schema_collections WHERE name = 'YourSchemaName';.
  • Re-import the schema collection if it appears truncated or missing definitions using CREATE XML SCHEMA COLLECTION.

Alternative or Verification Steps

  • Verification: Execute the modified query in isolation within a new SSMS query window. If the query returns the XML result set without throwing Error 9315, the constant expression fix was successful.
  • Alternative: If dynamic naming is a hard business requirement, bypass native XQuery constructors entirely by building the XML output using string concatenation (FOR XML PATH('')) combined with QUOTENAME() to sanitize dynamic tag names before casting the final result back to the XML data type.