Initial change number

What causes this issue?

The effectiviy of the material version &v1& should be determined using
a change number. However, no change number was entered.

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?

Enter a change number.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.