Currency &1 in contract &2 is different from the entered currency

What causes this issue?

The currency defined in contract &V2& is &V1&. You have entered a
different currency.
INCLUDE MM_IV_MELDUNGEN OBJECT DOKU ID TX

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 your entries.
If you delete your entries and choose ENTER, the system enters the
contract currency &V1&.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.