Users are able to add marketing plans in CRM and are then able to see these plans via the planner calendar in a calendar format. When users attempt to view the Planner calendar, they may receive the error:
String reference not set to an instance of a String. Parameter name: s
This occurs when a marketing plan exists with a start date using only month/year, rather than mm/dd/yyyy, and selecting the date filter of 'This Year'.
Download and install the latest patch, which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.