Focusing on the "Division undefined" part of this error message. This is a math calculation thing. Any sort of equation that causes the answer of "undefined" will trip this error.
A specific example would be if you set a field update to insert the result of Products divided by Price, where the price is $0:
Formula = Products/Price
Actual field update where you have 2 products worth $0 -- 2/$0 = undefined.
Prevent the field update from inserting an undefined value. This can be done with conditional statements either within the field update formula itself, or the formula of any formula fields being used in the update.
Utilizing the earlier example, we could write our field update formula like the one below to avoid the blank Price:
Formula = IF(Price = 0, 0, Products/Price)
This would update the field to read 0 if the Price was ever $0.