Sql-server – A member could not be added to a local group because the member has the wrong account type

The login of the session where you try to set permissions must have permissions.

So, the login you are using is a local admin? This means the local admin group does not have enough rights.

The GUI will run this too sp_addsrvrolemember. Although this says

Requires membership in the role to which the new member is being added.

So, the local admin group is not a member of sysadmin.

Edit:

To solve: Use a login that has rights. you can find one using sp_helpsrvrolemember

This is what I did:

1. Create a new domain user named sql_user, granting logon to the SQL Server target machine
2. On the target SQL Server machine, using the users control panel add the domain user to the group SQLServer2005MSSQLUser$HOST$MSSQLSERVER (beware there is a similar group named: SQLServer2005MSFTEUser$HOST$MSSQLSERVER which it seems the user does not need to be a member of)
3. Grant sql_user the ability to lock pages in memory if using the AWE extensions, see also: MSDN article
4. Change the SQL Server service to startup as the new domain user in the service control panel
5. Give sql_user write permission to the c:\program files\microsoft sql server directory and all subdirectories
6. Give sql_user write permission to the datafiles for all of your databases
7. Restart the database service
8. Check the Windows Error log for any errors