Tested on Dapper 1.42 and 1.50.2

The following sql statement will simulate creating a temp stored proc and execute it with dapper

create procedure #TestProcedure
as
begin

    -- basically a failed if statement, so the select is not happening and the stored proc return nothing
    if 1=0
    begin
        select 
            'Password' as ColumnName,
            'Cannot be the same as your username' as [Message]
    end

end

exec #TestProcedure

When using Query version, it works fine and no results return. When using QueryAsync version, it throws "No columns were selected" error.

I attached a code sample using microsoft localdb. The sample project is using Dapper 1.50.2 and structure similar to the one I submitted in #501

DapperBugReplication20160827.zip