You are not allowed to assign arch. object &1 to object type &2

What causes this issue?

You are not allowed to assign architectural object &V1& to a usage
object of type &V2&.

How to fix this error?

Change the Customizing settings so that this architectural object can be
assigned to a usage object of this type. You do this in the
<DS:SIMG.REFXV_TIVBDAROBJTYPE>Create Architectural Object Types</> IMG
activity.
Or:
Assign the architectural object to a different usage object. Or choose a
different architectural object for usage object &V2&.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.