Cannot map the lookup column, 'ID', because the column data type is a binary large object block (BLOB) There is a possibility that you might get this error while working in SSIS and trying to do a lookup to a csv file. In this case your destination columns might be of type (BLOB) - Long Text / Ntext and you might face this error And I tried a lot to convert the data inside the lookup column to varchar but it was constantly throwing an error : I tried : select cast(ID as varchar) as ID from table1 ......