One of the widely noticed issue in SSIS Excel connection manager is type guessing. For example, if there is a column with both numbers and characters and characters are coming after 10 rows of numbers. SSIS Excel connection manager predicts the column as of type numeric and outputs the character values as NULL. In order to handle this, we can edit the connection string and include these additional highlighted phrases to disable type guessing and set the type as TEXT so that all the values get captured properly Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\Excel Sources\Distributors\Customer.xlsx;Extended Properties="Excel 12.0 XML; IMEX=1 ;HDR=YES; TYPEGUESSROWS=0;IMPORTMIXEDTYPES=TEXT\ "; The connection string for an excel source is found by right-clicking the excel connection manager and going to properties.