The cannot insert NULL error appears, when you are migrating MS SQL to Oracle database.
To troubleshoot this scenario, perform the following:
Go to the database-table-column-mapping.properties file located at the following path:
For Windows: %ZENWORKS_HOME%\Novell\ZENworks\conf
For Linux: /etc/opt/novell/zenworks/conf
Open the database-table-column-mapping.properties file.
Append the Table name, Column, and the Replacement value according to the the database-table-column-mapping.properties file format.
IMPORTANT:If you donot provide a replacement value, then it will take an empty character as a replacement value.