Budget period cannot be activated for FM area &1

What causes this issue?

In FM area &V1&, the status of the budget period is set to <LS>Mandatory
</> or <LS>Optional</>. However, the budget period is not active for FM
posting and so cannot be used for budgeting.

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?

If you want to use the budget period for budgeting in this FM area, you
must first activate it for FM posting.
Otherwise, set the status to <LS>Not used</> in budgeting.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.