Line items do not balance in &1

What causes this issue?

You are trying to post a Journal Entry where the line items do not
balance in '&V1&' with the following details:
amount '&V2&' and currency key '&V3&'.

System Response

A posting without balancing line items is not possible.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.