Account assgt. cats. in agreement and requisition incompatible

What causes this issue?

For this <GL:purchase_requisition>purchase requisition</>,
<GL:account_assignment_category>account assignment category</> &V1& has
been defined. However, the account assignment category defined in the
<GL:outline_agreement>outline agreement</> to which this requisition is
assigned is &V2&.

How to fix this error?

Is the number of the outline agreement correct?
Have you entered the correct account assignment category in the
purchase requisition?

Error message extract from SAP system. Copyright SAP SE.