Invalid posting period for company code &1

What causes this issue?

You tried to post the settlement document. However, the posting period
is not open for the company.

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 a valid posting period in the following customizing settings
under <LS>Financial Accounting </>-><LS> Financial Accounting Global
Settings </>-><LS> Ledgers </>-><LS> Fiscal Year and Posting Periods
</>-><LS> Posting Periods</>.
Define variants for open posting periods in the customizing activity<LS>
Define Variants for Open Posting Periods</>.
Assign the posting period variant to the company code in the customizing
activity <LS>Assign Variants to Company Code</>.
Maintain the right posting period in the customizing activity <LS>Open
and Close Posting Periods</>.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.