500 as response when hitting an api

I have added an api in kong-EE but I am getting following error-

2018/07/05 16:12:33 [error] 62940#0: *5520 lua entry thread aborted: runtime error: /usr/local/share/lua/5.1/kong/core/plugins_iterator.lua:63: attempt to index field ‘cache’ (a nil value)
stack traceback:
coroutine 0:
/usr/local/share/lua/5.1/kong/core/plugins_iterator.lua: in function ‘load_plugin_configuration’
/usr/local/share/lua/5.1/kong/core/plugins_iterator.lua:202: in function ‘(for generator)’
/usr/local/share/lua/5.1/kong/init.lua:441: in function ‘rewrite’
rewrite_by_lua(nginx-kong.conf:92):2: in function <rewrite_by_lua(nginx-kong.conf:92):1>, client:, server: kong, request: “GET / HTTP/1.1”, host: “example.com