Company code & not assigned to Ledger &, but still required posting

What causes this issue?

At the activity/company code/ledger level, you defined that the company
code has to post to the ledger. However, this assignment is missing at
company code/ledger level. An update cannot therefore be made in
General Ledger.

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?

Check tables T886A, T886B and T882 with regard to the values entered.
<DS:TRAN.GCB1>Make assignment</>

Error message extract from SAP system. Copyright SAP SE.