Function &: Import parameter & does not have the correct type (pool)

What causes this issue?

The system checked the interface defined for function &V1&. It
compares it with the interface of reference function &V3&. During this
check, the system determined that import parameter &V2& does not
feature the same type as the reference parameter.

System Response

The system continues the check.

How to fix this error?

Correct the interface of function &V1&.

Error message extract from SAP system. Copyright SAP SE.