A common problem with SUM, is when the tool is attempted to be started and in browser the following error is being displayed:
“Not Found
Unable to locate the requested resource”
Even if after multiple attempts and maybe after a hostagent update, the same error is being displayed.
In this case there is a problem with one of host agent processes that remained hanged and if you check the processes at OS level you will notice 4 processes associated to the host agent:
ps -ef | grep host
root 7183 6053 0 17:29:32 ? 0:08 /usr/sap/hostctrl/exe/saphostexec pf=/usr/sap/hostctrl/exe/host_profile
root 24899 6053 0 15:50:32 ? 0:03 /usr/sap/hostctrl/exe/saposcol -l -w60 pf=/usr/sap/hostctrl/exe/host_profile
sapadm 24829 6053 0 15:50:31 ? 0:02 /usr/sap/hostctrl/exe/sapstartsrv pf=/usr/sap/hostctrl/exe/host_profile -D
root 24826 6053 0 15:50:30 ? 0:00 /usr/sap/hostctrl/exe/saphostexec pf=/usr/sap/hostctrl/exe/host_profile
The first process, that you can see with a different timestamp, it is the hanged one, kill this process and retry opening SUM tool, it should start successfully now.
Normally for hostagent, you should only see 3 process all the time, something similar to this:
sapadm 15877 28579 0 Jun 24 ? 206:27 /usr/sap/hostctrl/exe/sapstartsrv pf=/usr/sap/hostctrl/exe/host_profile -D root 16692 28579 0 Jun 24 ? 559:45 /usr/sap/hostctrl/exe/saposcol -l -w60 pf=/usr/sap/hostctrl/exe/host_profile root 15793 28579 0 Jun 24 ? 14:12 /usr/sap/hostctrl/exe/saphostexec pf=/usr/sap/hostctrl/exe/host_profile