Attempting to clone content between ArcGIS Enterprise deployments when authenticated using oauth 2.0 (using the client_id parameter per Working with different authentication schemes | ArcGIS API for Python | Esri Developer) results in the following error:
_ItemCreateException: ('Failed to create Feature Service clone_test: You do not have permissions to access this resource or perform this operation.\n(Error Code: 403)', <Item title:"clone_test" type:Feature Layer Collection owner:username>)
Content cloning using ArcGIS API for Python is commonly used for migration and content promotion between environment tiers. Since oauth 2.0 is the only way to authentication to ArcGIS Enterprise using SAML from the ArcGIS API for Python, organizations that do not allow utilization of Portal's built-in user store are unable to clone content.
Reference: BUG-000144380 for Portal for ArcGIS
