Item can only be changed in the external system

What causes this issue?

All items in this G/L account will be transferred individually into the
central system. This means that it will not be possible to change any
data in the local system after this transfer has taken place.

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?

Change this item in the appropriate document in the central system.

Error message extract from SAP system. Copyright SAP SE.