External company codes are not defined here

What causes this issue?

You have entered a company code which is characterized as a
<ZH>External company code</>. However, items for foreign company
codes can only be entered via the function provided for this
<LS>Goto -> Ext. company codes</>.

System Response

The company code is rejected.

How to fix this error?

Enter a company code that is not characterized as an external
company code.

Error message extract from SAP system. Copyright SAP SE.