This exception occurs when a lead or contact has an owner exchange and each of these owners involved does not view the records of each other.
If there is a task created in this lead or contact and this task is listed in the My Open Tasks portlet of the first user, then this exception error occurs.
The error occurs in the getModuleClassNameByModel function of the ContactsStateMetadataAdapter.php file because the user can not determine the lead's state.
My solution was to add the 'state' parameter to the check that occurs in the__get function of the SecurableItem.php file.
Later I'll be attaching the full patch I'm using.