120157: The following fields are missing from the append layer and field mapping: <value>.

Description

Input layer fields will only be appended to if they have a matching field in the append layer or are mapped to in the field mapping parameter. Fields not appended to will be populated with null values.

Solution

This is a warning and should be expected if you did not map these fields in the Append Fields or Append Expressions parameter.

Use the field mapping parameter to map fields with different names or to append fields with calculated values.