Valid From is not specified

What causes this issue?

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

System Response

If the start of the validity period is missing, the system does not
create any follow-up/replacement material relationships.

How to fix this error?

Enter the current date or a date in the future as the start of the
validity period. The start of the validity period has to be earlier than
its end date.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.