Extension & has successor &

What causes this issue?

The release can only be canceled if the current extension does not have
a successor yet.
Extension &v1&, however, has successor &v2&.

System Response

Release cannot be canceled.

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.

Error message extract from SAP system. Copyright SAP SE.