Class for order classification has not been generated

What causes this issue?

To be able to classify orders for order selection or order
summarization in the information system for Cost Object Controlling,
you must first:
select the characteristics that are active in your system
generate the characteristics that you selected
generate the class in which these characteristics are to be included
You do this in Customizing under <LS>Choose and generate
characteristics</>.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Go into Customizing and process the step <LS>Choose and generate
characteristics</>.

Error message extract from SAP system. Copyright SAP SE.