The definition of the validity intervals must be gap-free

What causes this issue?

The current assignments do not form an uninterrupted series. Under
certain circumstances, this is not permitted. In the following cases,
gaps are not permitted.
If multiple assignment is activated and a main assignment is maintained,
this assignment must be defined without gaps to 31.12.9999.
If the method <ZK>VALIDITY_PERIOD_CHECK</> of the BAdI
<ZK>BADI_MATGRP_HIER_CHK</> was used to forbid gaps, all assignments
must be (including the secondary assignments when multiple assignment is
activated) without gaps.
If the method <ZK>ARTICLE_MANDATORY_CHECK</> of the BAdI
<ZK>BADI_MATGRP_HIER_CHK</> was used to activate a mandatory assignment,
there must be at least one assignment with uninterrupted validity to
31.12.9999.
When multiple assignment is valid, the check for gaps is run for all
assignments in a category. When multiple assignment is not valid, the
check for gaps is run for all assignments in the entire hierarchy.

System Response

The system cannot transfer the entered assignments.

How to fix this error?

Adjust the assignments to ensure that there are no gaps.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.