How to fix Error 6102 on Windows Server 2025 / Windows 11

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Why This Error Happens

Error 6102 occurs when the login attempting to run the KILL statement lacks the server-level permission SQL Server requires to terminate another session. In SQL Server 2025 (as in all supported versions), running KILL requires the ALTER SERVER STATE permission, which is granted by default only to members of the sysadmin or processadmin fixed server roles. The most likely cause is that the login issuing the command is neither a member of one of these roles nor has been explicitly granted ALTER SERVER STATE. Port conflicts and corrupted files are not relevant here, since they would produce connectivity or startup errors rather than a permissions-based failure.

Step-by-Step Resolution Guide

Step 1: Identify the Affected Login

  • Connect to the instance using SQL Server Management Studio (SSMS) on Windows 11 or Windows Server 2025.
  • In a new query window, determine which login is currently connected and attempting the KILL statement:
SELECT SUSER_SNAME() AS CurrentLogin, ORIGINAL_LOGIN() AS OriginalLogin;
  • If you need to confirm the login tied to the session you are trying to kill, run:
SELECT session_id, login_name, status
FROM sys.dm_exec_sessions
WHERE session_id = <target_session_id>;

Step 2: Review the Login’s Current Permissions

  • Check whether the login is a member of a fixed server role that includes KILL rights:
SELECT IS_SRVROLEMEMBER('sysadmin', 'DOMAIN\LoginName') AS IsSysadmin,
       IS_SRVROLEMEMBER('processadmin', 'DOMAIN\LoginName') AS IsProcessAdmin;
  • Check the login’s explicit server-level permissions:
SELECT pr.name AS LoginName, pe.permission_name, pe.state_desc
FROM sys.server_permissions pe
JOIN sys.server_principals pr ON pe.grantee_principal_id = pr.principal_id
WHERE pr.name = 'DOMAIN\LoginName';
  • If the login has neither ALTER SERVER STATE listed nor membership in sysadmin/processadmin, this confirms the root cause.

Step 3: Grant the Required Permission

  • Assign only the minimum permission needed to resolve the issue, following least-privilege principles.
  • To grant the specific permission without adding full role membership:
GRANT ALTER SERVER STATE TO [DOMAIN\LoginName];
  • Alternatively, if the login should have broader session-management rights going forward, add it to the processadmin fixed server role instead:
ALTER SERVER ROLE processadmin ADD MEMBER [DOMAIN\LoginName];
  • Avoid granting sysadmin solely to resolve this error unless the login legitimately requires full administrative access.

Step 4: Reconnect and Retry

  • Close all open SSMS query windows associated with the affected login so the new permission is reflected in the session’s token.
  • Open a new query window, connect as DOMAIN\LoginName, and rerun the statement against the target session:
KILL <target_session_id>;
  • Confirm the session terminates without returning Error 6102.

Step 5: Review the Error Log If the Error Persists

  • If the permission change does not resolve the issue, review the SQL Server error log on the Windows Server 2025 host.
  • Default path for a default instance:
C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG

(Adjust the instance folder name, e.g., MSSQL17.<InstanceName>, if using a named instance.)

  • Alternatively, review the log directly from SSMS under Management > SQL Server Logs, or query it via T-SQL:
EXEC sys.xp_readerrorlog 0, 1, N'permission';
  • Look for related login failures, role membership changes, or permission denial entries around the time of the error.

Alternative or Verification Steps

  • Verify the fix: While connected as the affected login, confirm the permission is active:
SELECT * FROM fn_my_permissions(NULL, 'SERVER')
WHERE permission_name = 'ALTER SERVER STATE';

Then execute KILL <session_id>; and confirm the target session ends successfully.

  • Alternative if the primary steps fail: Test the KILL statement using a login with confirmed administrative rights, such as sa or another sysadmin member, to verify the session can be terminated at all. If the administrative login succeeds, this confirms the issue is isolated to the original login’s permissions rather than a broader instance-level problem.