diff --git a/lua/apisix.lua b/lua/apisix.lua
index e95bb087..8c5a8f27 100644
--- a/lua/apisix.lua
+++ b/lua/apisix.lua
@@ -31,6 +31,10 @@ end
 
 local function run_plugin(phase, filter_plugins, api_ctx)
     api_ctx = api_ctx or ngx.ctx.api_ctx
+    if not api_ctx then
+        return
+    end
+
     filter_plugins = filter_plugins or api_ctx.filter_plugins
     if not filter_plugins then
         return
@@ -66,7 +70,7 @@ function _M.rewrite_phase()
     local ok = router():dispatch(method, uri, api_ctx)
     if not ok then
         core.log.warn("not find any matched route")
-        return core.response.say(404)
+        return core.response.exit(404)
     end
 
     local local_plugins = core.lrucache.global("/local_plugins", nil,
@@ -103,7 +107,7 @@ end
 
 function _M.balancer_phase()
     local api_ctx = ngx.ctx.api_ctx
-    if not api_ctx.filter_plugins then
+    if not api_ctx or not api_ctx.filter_plugins then
         return
     end
 
diff --git a/lua/apisix/core/response.lua b/lua/apisix/core/response.lua
index d8970cab..f6909e84 100644
--- a/lua/apisix/core/response.lua
+++ b/lua/apisix/core/response.lua
@@ -9,7 +9,6 @@ local select = select
 local type = type
 local ngx_exit = ngx.exit
 local insert_tab = table.insert
-local clear_tab = table.clear
 local concat_tab = table.concat
 
 
@@ -19,9 +18,10 @@ local _M = {version = 0.1}
 local resp_exit
 do
     local t = {}
+    local idx = 1
 
 function resp_exit(code, ...)
-    clear_tab(t)
+    idx = 0
 
     if type(code) ~= "number" then
         insert_tab(t, code)
@@ -39,15 +39,19 @@ function resp_exit(code, ...)
             if err then
                 error("failed to encode data: " .. err, -2)
             else
-                insert_tab(t, body)
+                idx = idx + 1
+                insert_tab(t, idx, body)
             end
 
         else
-            insert_tab(t, v)
+            idx = idx + 1
+            insert_tab(t, idx, v)
         end
     end
 
-    ngx_say(concat_tab(t))
+    if idx > 0 then
+        ngx_say(concat_tab(t, "", 1, idx))
+    end
 
     if code then
         ngx_exit(code)
diff --git a/lua/apisix/plugins/example-plugin.lua b/lua/apisix/plugins/example-plugin.lua
index 5df17f50..577943e8 100644
--- a/lua/apisix/plugins/example-plugin.lua
+++ b/lua/apisix/plugins/example-plugin.lua
@@ -36,8 +36,7 @@ end
 
 function _M.access(conf, ctx)
     core.log.warn("plugin access phase, conf: ", core.json.encode(conf))
-    -- core.log.warn(" ctx: ", core.json.encode(ctx, true))
-    ngx.say("hit example plugin")
+    -- return 200, {message = "hit example plugin"}
 end