First delete the old database view

What causes this issue?

When activating a transparent matchcode ID, the view on the database
already existing for this matchcode did not match the revised
matchcode version. This could be due a change in the matchcode field
structure (e.g. because fields were added, deleted or exchanged) or to
the matchcode selection condition.

System Response

In such cases, activation must be cancelled as otherwise the matchcode
description in the ABAP/4 Dictionary will no longer match the view
created in the database. Accessing this view would therefore result in
the display of incorrect data or in a runtime error.

How to fix this error?

First delete the database view belonging to the particular matchcode
ID. Use the database utility. You can branch there directly
from the matchcode ID maintenance screen with the corresponding option
in the "Help" menu. Call the activation again after deleting the
database view.

Error message extract from SAP system. Copyright SAP SE.