diff --git a/homeassistant/components/automation/event.py b/homeassistant/components/automation/event.py
index d8c32fde86d..6f750245df9 100644
--- a/homeassistant/components/automation/event.py
+++ b/homeassistant/components/automation/event.py
@@ -36,11 +36,12 @@ def async_trigger(hass, config, action):
     @callback
     def handle_event(event):
         """Listen for events and calls the action when data matches."""
-        try:
-            event_data_schema(event.data)
-        except vol.Invalid:
-            # If event data doesn't match requested schema, skip event
-            return
+        if event_data_schema:
+            try:
+                event_data_schema(event.data)
+            except vol.Invalid:
+                # If event data doesn't match requested schema, skip event
+                return
 
         hass.async_run_job(action, {
             'trigger': {
diff --git a/homeassistant/const.py b/homeassistant/const.py
index ca438f35102..3a2ee824dda 100644
--- a/homeassistant/const.py
+++ b/homeassistant/const.py
@@ -2,7 +2,7 @@
 """Constants used by Home Assistant components."""
 MAJOR_VERSION = 0
 MINOR_VERSION = 56
-PATCH_VERSION = '1'
+PATCH_VERSION = '2'
 __short_version__ = '{}.{}'.format(MAJOR_VERSION, MINOR_VERSION)
 __version__ = '{}.{}'.format(__short_version__, PATCH_VERSION)
 REQUIRED_PYTHON_VER = (3, 4, 2)
diff --git a/homeassistant/helpers/entity_component.py b/homeassistant/helpers/entity_component.py
index f6e9c1da7f8..e805f277483 100644
--- a/homeassistant/helpers/entity_component.py
+++ b/homeassistant/helpers/entity_component.py
@@ -370,6 +370,12 @@ class EntityPlatform(object):
 
     def add_entities(self, new_entities, update_before_add=False):
         """Add entities for a single platform."""
+        # That avoid deadlocks
+        if update_before_add:
+            self.component.logger.warning(
+                "Call 'add_entities' with update_before_add=True "
+                "only inside tests or you can run into a deadlock!")
+
         run_coroutine_threadsafe(
             self.async_add_entities(list(new_entities), update_before_add),
             self.component.hass.loop).result()