Accrual object is not configured for release postings.

What causes this issue?

Releasing accruals will post journal entries.

System Response

To enable such release postings, the transaction types FP and optionally
also FL need to be assigned to a posting schema for all accrual item
types for which accruals shall be released.
This can be done in IMG activity <DS:SIMG.V_TACE_ITEMTYPES>Assign
Accrual Item Types to Journal Entry Types and Posting Schemas</>.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.