Document MS_WMS_ERROR_STATUS_CODE

en/mapfile/config.txt

@@ -154,6 +154,7 @@ A full sample config file is shown below:
       # MS_OPENLAYERS_JS_URL "http://openlayers.org/api/OpenLayers.js"
       # MS_TEMPPATH "/tmp"
       # MS_MAX_OPEN_FILES 200 # maximum number of open files allowed on Windows
+      # MS_WMS_ERROR_STATUS_CODE "ON"  # enable HTTP status code 4xx and 5xx in case of errors on WMS requests
     END
 
     #

en/ogc/wms_server.txt

@@ -2165,6 +2165,37 @@ Vendor specific WMS parameters
 .. index::
    pair: WMS; Cascading requests
 
+HTTP status error codes
+-----------------------
+
+The OGC WMS specification is not explicit about which HTTP status error code
+servers should return in case of errors. Traditionaly most WMS implementation
+return "200 OK" in those situations. Starting with MapServer 8.4, it is
+possible to define the ``MS_WMS_ERROR_STATUS_CODE`` configuration option to ``ON``
+in the CONFIG.ENV section of the MapServer configuration file to ask MapServer
+to return HTTP 4xx or 5xx status codes in case of error.
+
+
+.. code-block:: mapfile
+
+
+  CONFIG
+    #
+    # Environment variables
+    #
+    ENV
+      #
+      # Limit Mapfile Access
+      #
+      # MS_MAP_NO_PATH "1"
+      MS_MAP_PATTERN "^/opt/mapserver" ## required when referencing mapfiles by path
+      # MS_MAP_BAD_PATTERN "[/\\]{2}|[/\\]?\\.+[/\\]|,"
+
+      # Enable HTTP status code 4xx and 5xx in case of errors on WMS requests
+      MS_WMS_ERROR_STATUS_CODE "ON"
+    END
+  END
+
 Cascading WMS Requests
 ----------------------