4.1 SP2 upgrade breaks list items widget - Object reference not set to an instance of an object
Hello Mike,
This has been outlined in the Upgrade notes in the announcement:
Lists module: After upgrade, replace all List controls in "Expandable" mode
Please check the whole announcement here - http://www.sitefinity.com/devnet/forums/sitefinity-4-x/general-discussions/sitefinity-4-1-sp2-is-released.aspx