Action manager: Customize action group '&1' correctly

What causes this issue?

Customizing of the action manager for this list contains errors. The
error is in action group &V1&.
No details concerning the cause of the error could be ascertained.

System Response

The user actions will not work correctly in this screen.

How to fix this error?

The action manager definition for this list must be revised in the area
of action group &V1&.

Error message extract from SAP system. Copyright SAP SE.