Troubleshooting Guide: Error 7857 — Native SOAP Parameter Naming Violation

Why This Error Happens

This error occurs when a stored procedure or function exposed through a SQL Server Native SOAP/HTTP endpoint contains parameter names that violate the strict XML-compliant naming rules required by the SOAP serialization layer. Common causes include parameter names starting with numbers, containing special characters (such as #, @@, spaces, or hyphens), or using reserved/deprecated naming conventions that were permitted in legacy T-SQL but are no longer accepted by the modern SOAP endpoint parser in SQL Server 2025. Because the SOAP layer must map parameters directly to XML schema elements, any name that cannot be translated into a valid XML identifier triggers an immediate rejection at endpoint invocation time.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Procedure and Parameter

Open SQL Server Management Studio (SSMS) and locate the exact procedure referenced in the error message (the %.*ls placeholder will show the parameter name in the actual error output).
Run the following query to list all parameters for suspect procedures:

  SELECT OBJECT_NAME(object_id) AS ProcName, name AS ParamName
  FROM sys.parameters
  WHERE OBJECT_NAME(object_id) = 'YourProcedureName';

Check for leading digits, special characters, or double-underscore prefixes (e.g., @1stValue, @order#id, @__legacyParam).

Step 2: Rename Non-Compliant Parameters

Edit the procedure definition using ALTER PROCEDURE and rename parameters to comply with XML NCName rules (must start with a letter or underscore, followed only by letters, digits, underscores, hyphens, or periods).
Example fix:

  ALTER PROCEDURE dbo.GetOrderData
      @OrderId INT,        -- renamed from @1OrderId
      @CustomerName NVARCHAR(100)
  AS
  BEGIN
      SELECT * FROM Orders WHERE OrderID = @OrderId;
  END

Update any client-side SOAP request templates or WSDL caches referencing the old parameter names.

Step 3: Update the HTTP Endpoint Binding

Navigate to the endpoint configuration in SSMS under Server Objects > Endpoints.
Drop and recreate the SOAP endpoint binding to force SQL Server to regenerate the WSDL metadata with the corrected parameter names:

  DROP ENDPOINT YourSoapEndpoint;
  CREATE ENDPOINT YourSoapEndpoint
      STATE = STARTED
      AS HTTP (PATH = '/sql/soap', PORT = (8080))
      FOR SOAP (WEBMETHOD 'GetOrderData' (NAME = 'YourDB.dbo.GetOrderData'), WSDL = DEFAULT);

Step 4: Restart the SQL Server HTTP Listener Service

On Windows Server 2025 / Windows 11, open Services.msc and restart the SQL Server HTTP Listener service (or run net stop http / net start http from an elevated prompt if using the HTTP.sys shared listener).
This clears cached WSDL schema definitions that may still reference the old, invalid parameter names.

Alternative or Verification Steps

Re-run the SOAP client call or browse to http://<server>:8080/sql/soap?wsdl to confirm the WSDL generates without errors and the parameter names appear correctly formatted.
If the error persists, bypass Native SOAP entirely and migrate the procedure call to a REST-based endpoint via SQL Server’s built-in HTTP API, which does not enforce the same XML NCName restrictions.