
Does user account has db_owner permissions on all databases? Ensure that it has permissions at least on configuration database and on all content databases (you may need to go through all of them one by one and check). Although it will be simpler to add on all databases used by Sharepoint (Search, User profiles, Taxonomy, etc). Often such problems are fixed by granting shell admin rights to the current user:
Get-SPDatabase | Add-SPShellAdmin -Username CONTOSO\User1