Marketing project &1 not set to active; higher-level project is inactive

What causes this issue?

A higher-level marketing project in the hierarchy is inactive.

System Response

The system has not set marketing project &1 to active.

How to fix this error?

In the Marketing Planner, set the higher-level marketing project to
active.

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.