I ran into a problem several years ago with the upsizing wizard. I don't remember the exact details but it had something to do with date/time fields. The problem was either caused by SQL Server having a more limited range of dates available in the datetime field that Access has in its equivalent or the Upsizing Wizard chose the smalldatetime when it should have picked the datetime data type. Regardless of the cause, the result was overflow-type errors when the wizard ran. So, if you run into errors like this, look at the data fields in the table that errors out and you'll probably find some data that won't fit into SQL Server for one of the above reasons.