What is the likely cause of a 500 server error during Advanced Mapping?

The likely cause of a 500 server error during Advanced Mapping is when the administrator is trying to map to an unsupported field type. Advanced Mapping relies on specific data structures and field types to function correctly. If the mapping attempts to link to a field type that the system does not support, it can trigger a server error. In this case, it indicates that the server encountered an unexpected condition that prevented it from fulfilling the request.

While modifying or deleting a mapped field can lead to issues, typically this results in a different kind of error rather than a server error. Additionally, mapping to a managed package object can also lead to complications, but if the field types align correctly, it is often manageable without causing a server error. Validation rules may present issues at the point of data entry but wouldn’t usually lead to a server error in the mapping process itself. Thus, unsupported field types are the primary reason behind the 500 server error in this context.