How to fix Error 2379 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 2379 – Invalid XML Name

Why This Error Happens

Error 2379 occurs when SQL Server attempts to generate or parse XML data (such as through FOR XML clauses, XML schema collections, or column/element names) and encounters an identifier that violates XML naming rules. This typically happens when a column name, alias, or element name contains illegal characters (such as spaces, symbols, or a leading digit) that are valid in T-SQL but not permitted in the W3C XML specification. It can also surface when corrupted metadata or a malformed XML schema collection forces SQL Server to reference an invalid name during serialization.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Column or Alias

  • Review the exact query or stored procedure referenced in the error message, paying attention to the %ls placeholder which usually contains the invalid name.
  • Check for column names or aliases containing spaces, hyphens, special characters (#, @, $ in certain positions), or names starting with a numeral.
  • Run the query in SQL Server Management Studio (SSMS) 21 with SET FMTONLY ON or a limited TOP 1 execution to isolate the exact FOR XML segment causing the failure.

Step 2: Apply Valid XML Aliasing

  • Rewrite the query to assign XML-safe aliases to any problematic columns using square brackets, ensuring the alias starts with a letter or underscore and contains no spaces.
  • Example fix: Change SELECT [Order #] FROM Sales FOR XML AUTO to SELECT [Order #] AS OrderNumber FROM Sales FOR XML AUTO.
  • If using FOR XML PATH, explicitly define safe element names using the AS syntax for every computed or aggregated column.

Step 3: Validate XML Schema Collections

  • If the error originates from a typed XML column, open the associated XML Schema Collection (XSD) in SSMS under Databases > [YourDB] > Programmability > Types > XML Schema Collections.
  • Verify that the targetNamespace and element definitions comply with standard XML naming conventions (no leading numbers or invalid symbols).
  • If the schema is corrupted, drop and recreate it using DROP XML SCHEMA COLLECTION followed by CREATE XML SCHEMA COLLECTION with the corrected .xsd definition file.

Step 4: Check for Hidden Whitespace or Unicode Characters

  • Inspect the source data or variable names for non-printable Unicode characters that may have been introduced via copy-pasting from external documents or web sources.
  • Use the T-SQL function SELECT ASCII(SUBSTRING(ColumnName, 1, 1)) to detect hidden characters at the start of a string being used as an XML node name.
  • Clean the data using REPLACE() or TRIM() functions before passing it into the FOR XML command.

Alternative or Verification Steps

  • Verification: Re-run the original query or application call that triggered Error 2379; confirm the XML output renders correctly in the SSMS results grid without throwing a parser exception.
  • Alternative: If renaming columns is not feasible due to application dependencies, wrap the query in a subquery or CTE that renames the columns to XML-compliant aliases before the final FOR XML conversion is applied.