diff --git a/chaos_monkey/__init__.py b/chaos_monkey/__init__.py
deleted file mode 100644
index 05a457b0c..000000000
--- a/chaos_monkey/__init__.py
+++ /dev/null
@@ -1 +0,0 @@
-__author__ = 'itamar'
diff --git a/chaos_monkey/config.py b/chaos_monkey/config.py
index addb9fd54..b26c911b0 100644
--- a/chaos_monkey/config.py
+++ b/chaos_monkey/config.py
@@ -45,6 +45,11 @@ def _cast_by_example(value, example):
 
 class Configuration(object):
     def from_dict(self, data):
+        """
+        Get a dict of config variables, set known variables as attributes on self.
+        Return dict of unknown variables encountered.
+        """
+        unknown_variables = {}
         for key, value in data.items():
             if key.startswith('_'):
                 continue
@@ -55,9 +60,11 @@ class Configuration(object):
             try:
                 default_value = getattr(Configuration, key)
             except AttributeError:
-                raise
+                unknown_variables[key] = value
+                continue
 
             setattr(self, key, _cast_by_example(value, default_value))
+        return unknown_variables
 
     def as_dict(self):
         result = {}
diff --git a/chaos_monkey/control.py b/chaos_monkey/control.py
index f8f3e3ee0..cdeb47a76 100644
--- a/chaos_monkey/control.py
+++ b/chaos_monkey/control.py
@@ -124,7 +124,7 @@ class ControlClient(object):
             return
 
         try:
-            WormConfiguration.from_dict(reply.json().get('config'))
+            unknown_variables = WormConfiguration.from_dict(reply.json().get('config'))
             LOG.info("New configuration was loaded from server: %r" % (WormConfiguration.as_dict(),))
         except Exception, exc:
             # we don't continue with default conf here because it might be dangerous
@@ -132,6 +132,23 @@ class ControlClient(object):
                       WormConfiguration.current_server, reply._content, exc)
             raise Exception("Couldn't load from from server's configuration, aborting. %s" % exc)
 
+        if unknown_variables:
+            ControlClient.send_config_error()
+
+    @staticmethod
+    def send_config_error():
+        if not WormConfiguration.current_server:
+            return
+        try:
+            requests.patch("https://%s/api/monkey/%s" % (WormConfiguration.current_server, GUID),
+                                data=json.dumps({'config_error': True}),
+                                headers={'content-type': 'application/json'},
+                                verify=False,
+                                proxies=ControlClient.proxies)
+        except Exception, exc:
+            LOG.warn("Error connecting to control server %s: %s", WormConfiguration.current_server, exc)
+            return {}
+
     @staticmethod
     def check_for_stop():
         ControlClient.load_control_config()
diff --git a/chaos_monkey/requirements.txt b/chaos_monkey/requirements.txt
index 8c77333f9..34f24c78f 100644
--- a/chaos_monkey/requirements.txt
+++ b/chaos_monkey/requirements.txt
@@ -12,3 +12,5 @@ psutil
 PyInstaller
 ecdsa
 netifaces
+mock
+nose
diff --git a/chaos_monkey/test/__init__.py b/chaos_monkey/test/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/chaos_monkey/test/config__test.py b/chaos_monkey/test/config__test.py
new file mode 100644
index 000000000..fccde2f0d
--- /dev/null
+++ b/chaos_monkey/test/config__test.py
@@ -0,0 +1,45 @@
+# -*- coding: UTF-8 -*-
+# NOTE: Launch all tests with `nosetests` command from chaos_monkey dir.
+
+import json
+import unittest
+
+from mock import Mock, patch
+
+import control
+
+from config import GUID
+
+
+class ReportConfigErrorTestCase(unittest.TestCase):
+    """
+    When unknown config variable received form the island server, skip it and report config
+    error back to the server.
+    """
+
+    config_response = Mock(json=Mock(return_value={'config': {'blah': 'blah'}}))
+
+    def teardown(self):
+        patch.stopall()
+
+    def test_config(self):
+        patch('control.requests.patch', Mock()).start()
+        patch('control.WormConfiguration', Mock(current_server='127.0.0.1:123')).start()
+
+        # GIVEN the server with uknown config variable
+        patch('control.requests.get', Mock(return_value=self.config_response)).start()
+
+        # WHEN monkey tries to load config from server
+        control.ControlClient.load_control_config()
+
+        # THEN she reports config error back to the server
+        control.requests.patch.assert_called_once_with(
+                "https://127.0.0.1:123/api/monkey/%s" % GUID,
+                data=json.dumps({'config_error': True}),
+                headers={'content-type': 'application/json'},
+                verify=False,
+                proxies=control.ControlClient.proxies)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/monkey_island/cc/main.py b/monkey_island/cc/main.py
index ccf3fe995..b05c42e70 100644
--- a/monkey_island/cc/main.py
+++ b/monkey_island/cc/main.py
@@ -86,6 +86,8 @@ class Monkey(restful.Resource):
             update['$set']['config'] = monkey_json['config']
         if 'tunnel' in monkey_json:
             update['$set']['tunnel'] = monkey_json['tunnel']
+        if 'config_error' in monkey_json:
+            update['$set']['config_error'] = monkey_json['config_error']
 
         return mongo.db.monkey.update({"guid": guid}, update, upsert=False)