I got the error as in the subject after I had registered a new webgate , done other necessary configurations and tried to access a WebCenter Portal page which I was trying to protect.
The error in the oblog.log said -
The error in the oblog.log said -
Request Failed for :
/index.html, Resp Code : [500]
OBWebGate_AuthnAndAuthz:
Cannot get message for ObAccessException_NO_AGENT_KEY
Oracle Support had a similar issue for Fusion Apps which didnot really help -
https://support.oracle.com/epmos/faces/DocumentDisplay?id=1534423.1
Finally , after using the OAM Tester , a colleague suggested to edit and re-copy Webgate related files from Output Directory of the OAM_Domain pertaining to the webgate to <OHS_Instance>/config/OHS/ohs1/webgate/config.
Hope this helps someone facing a similar issue.