No direct postings possible to G/L account &

What causes this issue?

No direct postings can be made to the G/L account (because
it is a <GL:reconciliation_account>reconciliation account</>).

System Response

The system cannot post the amount to this account.

How to fix this error?

INCLUDE MB_NA_SACHKONTO
If you have entered the G/L account manually, enter a different account
or cancel the account entered, so that the system determines an account
automatically.

Error message extract from SAP system. Copyright SAP SE.