Balance not zero: & debits: & credits: &

What causes this issue?

The system has discovered a difference between the debits and credits.
This difference lies outside the tolerance limits set.

System Response

The system cannot post the document.

How to fix this error?

If this message appears when you are processing a document online, you
can change the amounts or enter new items until you can post the
document.
IF &[SWITCH]S4H_DOCU_ON_PREMISE& = 'X'.
You can change the Invoice Verification type, so that the document can
be posted later in the background. If this message appeared when a
document was verified in the background, you can now process the
document.
ENDIF.

Error message extract from SAP system. Copyright SAP SE.