@Tom Burke Are you really checking what kind of command aere you executing in curl and what does every curl argument means? Before attaching the "hosts4.json" if you would have just checked the content of this file then you would know that the credentials which you are entering in curl command are Wrong ambari admin credential. # cat hosts4.json { "status": 403, "message": "Unable to sign in. Invalid username/password combination." } . As i do not know your ambari admin credentials hence i just gave you a dummy curl command and expected that you will change the values according to your cluster. ... View more

@Tom Burke It may be browser caching issue. So please try this: 1. Open the Web Browser in "Private Mode" (In Firefox) or "Incognito Mode" (in Chrome) and then try again. 2. If still you face the same issue then please try this to edit the "/etc/ambari-server/ambari.properties" file and then unset the value of the following two properties: FROM ------ http.strict-transport-security=max-age=31536000 views.http.strict-transport-security=max-age=31536000 TO ------ http.strict-transport-security=max-age= views.http.strict-transport-security=max-age= The restart ambari-server and then try accessing the UI again # ambari-server restart . ... View more