This trans. is not poss. unless valuation is carried out at the same time

What causes this issue?

You want to post a transaction that is not possible as long as
subsequent calculation of value for goods movements is active in your
system.

System Response

The system prevents the following postings when subsequent calculation
of value is active:
Goods movements with reference to
<DS:GLOS.3526C388AFAB52B9E10000009B38F974>production orders</>
Posting of <DS:GLOS.3526BEFDAFAB52B9E10000009B38F974>inventory
differences</>

How to fix this error?

Exit subsequent calculation of value with the error monitor
(transaction code <DS:TRAN.MBWO>MBWO</>), and use program
<DS:RE.RM07MWBU>RM07MWBU</> to valuate all goods movements that have
not yet been valuated.
Afterwards you can post all standard SAP transactions.

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.