Order & does not exist

What causes this issue?

You want to use order &V1& in automatic account assignment, but this
order does not exist.

System Response

The system does not permit you to make this entry.

How to fix this error?

The activities you need to carry out depend on the system you work in:
<ZH>Production system:</>
Correct your entry or create order &V1&.
<ZH>Test system:</>
If you want to transport the automatic account assignments into the
productive system at a later date, but you do not want to create all
the orders you require there in the test system, then you can
deactivate this message in the test system or change the message into a
warning or information only. However, if you do so, note that you are
responsible for ensuring that the order you entered exists in the
productive system, belongs to the correct controlling area, and is
assigned to the correct company code.
To change the message type, access the IMG and choose "General
Controlling" -> "Change Message Control". Enter the message ID (KI).
You can now create a new entry for the message number 621 that deviates
from the standard message type.
-> <DS:TRAN.OBA5>Message Control</>

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.