Blog discusses the root cause of the error that is undocumented and shows a way to troubleshoot it for indulging the error.
I dont like unreadable errors that I never understand so I started debugging the FMSAI_CACHE3_REFRESH_HTTP and found out that error is due to the authorization object S_RFC_ADM that is missing for my user. If you want to get a meaningful error at least try executing the function module RFC_READ_HTTP_DESTINATION giving INTEGRATION_DIRECTORY_HMI as the RFC destination that shows the appropriate error as given below.
After assigning the S_RFC_ADM authorization object the stupid error insxi_cache vanished.
Blogging it so that it can be useful to troubleshoot stupid errors like this.