No company code is assigned to plant &

What causes this issue?

The system tried to determine the company code for the plant specified.
However, no company code has been assigned to the plant.

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?

Maintain the assignment in Customizing.
<DS:TRANS.OX18>Proceed</>

Error message extract from SAP system. Copyright SAP SE.