How to fix Error 2277 on Windows Server 2025 / Windows 11

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Why This Error Happens

This error occurs when SQL Server’s FOR XML clause attempts to generate an XML element from a column or table alias that contains a character not permitted in XML tag names, such as spaces, symbols, or a leading numeric digit. SQL Server 2025 enforces strict XML naming conventions (per the W3C XML specification), so any alias like [Order #] or [1stName] will trigger Error 2277 instead of silently sanitizing the string. This is typically a query-design issue rather than a server configuration fault, but it can also surface after a migration when legacy column names or linked-server metadata contain illegal characters.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Column or Alias

  • Review the exact T-SQL query that raised Error 2277 in SQL Server Management Studio (SSMS) or Azure Data Studio.
  • Check the error message detail for the specific character %c reported — common culprits are spaces, #, $, @, or a tag starting with a digit.
  • Run the query with FOR XML PATH('') removed temporarily to isolate which column is being serialized into XML.

Step 2: Rename or Alias the Column Properly

  • Add a valid alias using square brackets, ensuring it starts with a letter or underscore and contains only letters, digits, hyphens, periods, or underscores.
  • Example fix:
SELECT [Order Amount] AS OrderAmount
FROM Sales.Orders
FOR XML PATH('Order'), ROOT('Orders')
  • If the issue stems from a physical column name, consider using sp_rename cautiously in a test environment first:
EXEC sp_rename 'Sales.Orders.Order #', 'OrderNumber', 'COLUMN';

Step 3: Validate Linked Server or Dynamic SQL Sources

  • If the query pulls from a linked server or dynamically built column list, inspect the source schema for illegal characters using sys.columns.
  • Run this diagnostic script to scan for problematic names:
SELECT name 
FROM sys.columns 
WHERE name LIKE '%[^a-zA-Z0-9_]%';
  • Correct any flagged names at the source or wrap them with safe aliases before they reach the FOR XML clause.

Step 4: Clear Cached Execution Plans (If Error Persists)

  • Occasionally a cached plan with the old alias structure causes the error to resurface even after correction.
  • Clear the plan cache for the affected database:
DBCC FREEPROCCACHE;
  • Re-run the corrected query to confirm the cached plan no longer references the invalid XML tag.

Alternative or Verification Steps

  • Re-execute the original query in SSMS; a successful XML result set (no Error 2277) confirms the fix.
  • As a quick workaround without renaming columns, wrap the problematic column in an inline alias directly within the SELECT statement (e.g., SELECT [Bad#Name] AS SafeName) rather than modifying the underlying table schema.