How to fix Error 3751 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 3751

Why This Error Happens

Error 3751 occurs when SP_DROPEXTENDEDPROC or DBCC DROPEXTENDEDPROC is used against an object that is not actually registered as an extended stored procedure, such as a regular stored procedure, scalar function, or system object. SQL Server validates the object type in sys.objects/sys.extended_procedures before allowing the drop operation, and a type mismatch (commonly %S_MSG reporting “stored procedure” instead of “extended stored procedure”) triggers this block. This typically happens after a migration, a naming collision, or when scripts written for legacy XP-based procedures are run against objects that were never created with sp_addextendedproc.

Step-by-Step Resolution Guide

Step 1: Confirm the Object Type Before Dropping

  • Run the following query to check how SQL Server classifies the object:
SELECT name, type, type_desc 
FROM sys.objects 
WHERE name = 'YourObjectName';
  • Look at the type_desc column — extended stored procedures will show EXTENDED_STORED_PROCEDURE, while regular ones show SQL_STORED_PROCEDURE.
  • If the type does not match XP, the drop command you are using is incorrect for this object.

Step 2: Use the Correct Drop Command for the Object Type

  • If the object is a standard stored procedure, use:
DROP PROCEDURE YourObjectName;
  • If the object is a scalar/table-valued function instead, use:
DROP FUNCTION YourObjectName;
  • Only use sp_dropextendedproc or DBCC DROPEXTENDEDPROC when sys.extended_procedures actually lists the object.

Step 3: Check for Naming Conflicts or Duplicate Objects

  • Search across all schemas to ensure there isn’t a naming collision:
SELECT s.name AS schema_name, o.name, o.type_desc 
FROM sys.objects o
JOIN sys.schemas s ON o.schema_id = s.schema_id
WHERE o.name = 'YourObjectName';
  • If duplicates exist in different schemas, fully qualify the object name (e.g., dbo.YourObjectName) in your drop statement to target the correct one.

Step 4: Validate Extended Procedure DLL Registration

  • If you expected this to be an XP, confirm it was registered properly using:
SELECT * FROM sys.extended_procedures;
  • If the procedure is missing from this list, it was never registered as an extended procedure — re-register it with sp_addextendedproc 'YourObjectName', 'YourDLL.dll'; if required, or abandon the XP drop approach entirely since SQL Server 2025 strongly discourages XPs in favor of CLR integration or external language extensions.

Step 5: Restart SSMS/Query Session and Re-Test

  • Close and reopen your SQL Server Management Studio (SSMS) session or query window to clear any cached metadata.
  • Re-run the corrected drop statement from Step 2 against the validated object.

Alternative or Verification Steps

  • Verify success by re-querying sys.objects for the target name — it should return no rows if the drop succeeded.
  • If the object still cannot be dropped due to dependency locks, check sys.sql_expression_dependencies for references and remove dependent objects first before retrying.