3800498 - Internal Server Error during SAP HANA Cockpit 2.0 logon - UAA token exchange fails with "tunneling socket could not be established, statusCode=403"

• Internal Server Error occurs after entering COCKPIT_ADMIN credentials and selecting Log On.
• Login fails during OAuth token exchange with XSA UAA.
• Error message (or similar) seen in cockpit-web-app.log: "Could not authenticate with UAA: Could not obtain access token ... tunneling socket could not be established, statusCode=403."

Or HANA Cockpit is accessible, however:

• when accessing the registered databases, additional login prompts, and the authentication failed with:
  Error: Invalid credentials
• authentication to the registered databases passed, but failed to open the Database Overview page with:
  Error: Cannot connect to backend service
  
  

• SAP HANA Cockpit 2.0
• SAP HANA XS Advanced

internal server error, cockpit login, uaa, oauth token, 403, tunneling socket, proxy, http_proxy, https_proxy, xs set-env, cockpit-web-app, cockpit-admin-web-app, cockpit-adminui-svc, cockpit-landscape-svc, token exchange, Invalid credentials, Cannot connect to backend service , KBA , HAN-CPT-CPT2 , SAP HANA Cockpit version 2 - based on XSA , Problem