Currency entered differs from currency & in PO &

What causes this issue?

The currency agreed in purchase order &V2& is &V1&. You have entered a
different currency.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
INCLUDE MM_IV_MELDUNGEN OBJECT DOKU ID TX
ENDIF.

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 what you entered.
If you delete your entry and press ENTER, the system will enter the
order currency &V1&.

Error message extract from SAP system. Copyright SAP SE.