Misprinted bills with a partial obstruction leave the Bureau of Engraving and Printing at an alarming rate. These types of errors can be purchased for a few dollar over face value to a couple hundred dollars. The value all depends on the severity of the error and the condition of the bill. These misprints are common. As you can imagine, there is a lot paper floating around the printing presses. It is not uncommon for that paper to get in the way of a printing.
The note below has a large missing portion of the second printing from where something physically prevented the print from making it to the bill. This white portion can be big or small. It can affect small pieces of the note. The serial number, seal, front, and back of the note could be affected. Keep in mind that if whatever caused the misprint (like a piece of paper) is still attached to the note then the note is worth much more.