Error during BAdI call: BAdI & &

What causes this issue?

The call of BAdI <ZH>&V1&</> returns invalid data. This error is
probably caused by the implementation of a method from the BAdI.

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?

Check the implementation of the relevant method(s), and the data
returned.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.