Error : Work terms records are required when you create or update assignments.

Summary:

I need to update the assignment ( business title) name for set of employees.

Content (required):

I used the spreadsheet loader and received the below error message when trying to upload the values.

Work terms records are required when you create or update assignments.

What is the reason for this error?

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):