Cannot access Fortigate web-config page (restarting fortigate services)

Declare:
- Fortigate with accessible interface thru ssh.
(may vary due to your organization policies. In common, gateway devices has disabled their ssh)

Problem:
Web-configuration page cannot be accessed due to services overload.

Action:
access your device using CLI, then execute below commands:

# get system performance top  <= this commands will show you all the running process in fortigate, 2nd collumn is the process-id. in our case, look for "httpsd" processes

Kill'em all:
# diagnose sys kill    <= restart "httpsd" process
# diagnose sys kill    <= restart another "httpsd" process
# diagnose sys kill    <= restart another "httpsd" process

Try to access your web-config again. It should be OK now..