Troubleshooting Attempt to de-reference null object error message in Salesforce Maps

Plotting or editing a Marker Layer - If you see this error while working with a Marker Layer, you should verify the following aspects:

• One or more of the fields referenced in the Marker Layer used for filters, marker pop-ups, or display options have been deleted from the object.
• The fields associated with the Base Object, such as the Priority field and those configured for the Map It button, have been deleted from the object.

Because Salesforce Maps stores these fields as text strings within Maps Objects in the backend, if a field is deleted, it is not automatically removed from any references to it within Maps.  In this scenario, you should verify whether the field(s) referenced in the layers or Base Objects have been deleted. If it has, the solution involves editing the layer to remove the field from the Marker Layer and then saving the changes. 

Adding to Schedule - Another common scenario where you might encounter the error message is when attempting to save a schedule. In such cases, you should verify the relatedTo field for the event and ensure that it is not blank. Additionally, when working with CG cloud visits, make sure that existing visits have a Planned Visit End Time. While CG cloud doesn’t mandate end times for visits, they are necessary for the visits to function correctly in Maps.