Transaction BOB is deprecated.

What causes this issue?

Usage of transaction BOB is deprecated.

System Response

System will not allow you to create or edit both custom and enhancement
business objects in transaction BOB.

How to fix this error?

For custom business object, please use either ABAP Development Tools or
transaction BOBX.
For enhancement business object, please use transaction BOBX.

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.