Hi Prasath Kanagaraj,
Sorry for the Inconvenience. The issue you are having is caused by the current system maintenance that is happening this week. Due to close of year processes, access to certain systems has been locked down. This system maintenance will end on November 12 at 11:59 pm EST and you will once again have access for self-service. If there are issues that you need to act on immediately, you can reach out to the Customer Care team and they can assist.
More information can be found on the Customer Care Community: Unable to Access Case Management from the Support Portal
Regards,
Heena