2109340 - Error "Missing Key Specification For Processing Node" while trying to update any details for an existing object using Migration/ Mass Data Maintenance

When trying to update any details for an existing object using Migration/ Mass Data Maintenance the following error occurs:
Missing key specification for processing node <any entity>.

SAP Business ByDesign

Taking Migration of Employee and User Data as example. 

1. Go to Business Configuration work center.
2. Go to Overview view
3. Select to Show All Configuration Elements and find the activity: Migration of Employee and User Data.
4. Select the link: Employee and User Data using the migration tool.
5. Select the uploaded migration template.
6. Execute Migration Step by Step.

Error Occurs "Missing key specification for processing node EMPLOYEE ROOT"

These errors occurs when trying to add a new field data to an existing object(Employee) which is not possible using Migration(Modify Already Existing Records) or Mass Data Maintenance. Only existing field values in a record can be modified using this option.

Add the new field value to an existing entity using Enhance Already Existing Records option in the migration tool with the following steps:

1. Go to Business Configuration work center.
2. Go to Overview view
3. Select to Show All Configuration Elements and find the activity: Migration of Employee and User Data.
4. Select the link: Migrate Employee and User Data Activity using the migration tool
5. Upload the file and select it.
6. Select the Properties button.
7. In the drop-down for Migration Mode, select Enhance Already Existing Records.
8. Click on Save.
9. Execute Migration Step by Step.

Migration, Data Enhancement, Entity Root, Validation, Update, Error, Enhancement, Missing, Specification, Processing, Node, Employee , KBA , SRD-CC-MIG-CNT , Migration: Content , How To