In 8.1 out-of-box on-premise deployment with all updates applied (as of today, update 2 SNC, web core and web model), an error is thrown in the Account Detail view Account Contacts tab and Opportunity Detail view Opportunity Contacts tab when sorting the grid by Contact.
The grid is set to use the NameLF calculated field value, but the column is set to sort on LastName. This generates an order by clause of "LASTNAME ASC, FIRSTNAME ASC, LASTNAME ASC" which causes the SQL error and results in a 500 error in the slxdata request.
This can be fixed by changing the sort field for the Contact column to NameLF, rebuilding and redeploying the web portal, and clearing cache on the browser in order to reload the javascript for the editable grid.
This is noted in Issue #: 14095532 reported 4/10/2014.
