The item you posted appears to be an issue within your ADFS identity provider. I suggest you contact your IDP resource to help you investigate further as it looks like you're also using custom code to perform the logout operation. This seems to be outside the domain of Portal for ArcGIS.
Hope this helps,
Hi Derek Law
Thanks for your answer
Having said that but If I try to logout using ArcGIS Portal though it gives me message "You've been successfully signed out" and redirects me to https://agsportal.abc.org/portal/sharing/rest/oauth2/signout But when I hit
->https://agsportal.abc.org/portal/home/index.html -> then Click on "Sign In"
->https://agsportal.emisk.org/portal/home/signin.html=In Sign in to Portal for ArcGIS options I chose "Using your abc account" then it directly opens https://agsportal.emisk.org/portal/home/index.html without asking username and password. Ideealy it should direct me to ADFS sign in page
Apologies for the late reply, I was out of the office on business travel the last 2 weeks.
Please open an incident with Esri Tech Support so they can investigate and help resolve your issue.