Function & not defined

What causes this issue?

You have called function &V1& within interactive reporting. However,
this function is not defined.

System Response

The system was not able to perform function &V1&.

How to fix this error?

If you did not call function &V1& via manual input, this message is
normally attributable to an internal program error. If necessary,
contact your system administrator.

Error message extract from SAP system. Copyright SAP SE.