diff --git a/README.md b/README.md
index cd98ee0..0d8e813 100644
--- a/README.md
+++ b/README.md
@@ -406,6 +406,10 @@ Jump between symbols with treesitter (with `]r` and `[r`)
 
 ### Diagnostic
 
+Visual studio code style show errors minimap in scroll bar area
+![diagnostic_scroll_bar](https://user-images.githubusercontent.com/1681295/128736430-e365523d-810c-4c16-a3b4-c74969f45f0b.jpg)
+
+
 Diagnostic in single bufer
 
 ![diagnostic](https://github.com/ray-x/files/blob/master/img/navigator/diag.jpg?raw=true)
diff --git a/lua/navigator/diagnostics.lua b/lua/navigator/diagnostics.lua
index f62c537..7d3c6c2 100644
--- a/lua/navigator/diagnostics.lua
+++ b/lua/navigator/diagnostics.lua
@@ -12,7 +12,7 @@ local path_cur = require"navigator.util".path_cur()
 diagnostic_list[vim.bo.filetype] = {}
 
 local function error_marker(result, client_id)
-  if _NgConfigValues.diag_scroll_bar_sign == nil then
+  if _NgConfigValues.diag_scroll_bar_sign == nil then -- not enabled or already shown
     return
   end
   local first_line = vim.fn.line('w0')
@@ -35,6 +35,10 @@ local function error_marker(result, client_id)
     return
   end
 
+  if _NG_VT_NS == nil then
+    _NG_VT_NS = vim.api.nvim_create_namespace("navigator_lua")
+  end
+
   vim.api.nvim_buf_clear_namespace(0, _NG_VT_NS, 0, -1)
 
   -- total line num of current buffer
@@ -133,6 +137,7 @@ local diag_hdlr = function(err, method, result, client_id, bufnr, config)
     error_marker(result, client_id)
   else
     vim.api.nvim_buf_clear_namespace(0, _NG_VT_NS, 0, -1)
+    _NG_VT_NS = nil
   end
 
 end