Flow is due before accrual/deferral key date, but not posted

What causes this issue?

The corresponding flow is due before the accrual/deferral key date,
but has not yet been posted; this may result in the incorrect amount
of expenses or revenues being displayed in financial accounting.

System Response

The flow is treated by the accrual/deferral function as if were already
posted, i.e. the related expenses or revenues are accrued/deferred,
where appropriate.

How to fix this error?

Post the flow to correct the amounts of expenses or revenues shown
in financial accounting.

Error message extract from SAP system. Copyright SAP SE.