In contract &1, currency &2 and exchange rate &3 are fixed

What causes this issue?

In contract &V1&, currency &V2& and exchange rate &V3& are fixed.
The currency &V4&, entered for the invoice document, is different from
these fixed specifications.

System Response

Further processing of the invoice document is only possible if the fixed
currency key matches the entered currency key.

How to fix this error?

If this check was made in dialog mode, you must correct the invoice
amount and the currency code.
To do this, enter currency key &V2&.
You can also delete the currency key on the entry screen. In this case,
the fixed currency key and exchange rate from the contract are copied
automatically.
If this message is generated by the background check, you must delete
the invoice and enter it again with the correct currency key.

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.