Something you might overlook as a SharePoint developer is the fact that when you are using STSADM commands to deploy your solution you are running under your own account context. This in contrast with actions that you perform using SharePoint central admin which will typically run under the context of the farm service account.
So if you need to deploy/upgrade farm based solutions using stsadm I would typically do the following:
- Add your account to the local Administrators group on the SharePoint server machine
- Add the user with the public role and db_owner role on the SharePoint database in SQL Server
For more background information – check out You receive error messages when you try to use the stsadm.exe command line tool to perform administrative operations in Windows SharePoint Services – this support article is written for 2007 but is still valid for 2010.