No account assignment category found with unknown consumption posting

What causes this issue?

You have completed sourcing in SAP Sourcing and now want to create a
purchasing document in the system. SAP Sourcing cannot transfer account
assignments. However, when you create a purchasing document, you must
have an account assignment. For this reason, you can only create
purchasing documents with the account assignment category <ZK>Unknown</>
from SAP Sourcing. However, you have not defined an account assignment
category with an unknown consumption posting in Customizing.

System Response

Since the system cannot find an account assignment category with an
unknown consumption posting, and this kind of category is required for
SAP Sourcing integration, the system terminates the creation of the
purchasing document.

How to fix this error?

Define the required account assignment category in Customizing for
<ZK>Materials Management</> under <ZK>Purchasing --> Account Assignment
--> Maintain Account Assignment Categories</>.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.