diff --git a/optimizely/config_manager.py b/optimizely/config_manager.py
index 35bdfa8e6..0c05d534a 100644
--- a/optimizely/config_manager.py
+++ b/optimizely/config_manager.py
@@ -212,15 +212,24 @@ def set_update_interval(self, update_interval):
         Args:
           update_interval: Time in seconds after which to update datafile.
         """
-        self.update_interval = update_interval or enums.ConfigManager.DEFAULT_UPDATE_INTERVAL
+        if not update_interval:
+            update_interval = enums.ConfigManager.DEFAULT_UPDATE_INTERVAL
+            self.logger.debug('Set config update interval to default value {}.'.format(update_interval))
+
+        if not isinstance(update_interval, (int, float)):
+            raise optimizely_exceptions.InvalidInputException(
+                'Invalid update_interval "{}" provided.'.format(update_interval)
+            )
 
         # If polling interval is less than minimum allowed interval then set it to default update interval.
-        if self.update_interval < enums.ConfigManager.MIN_UPDATE_INTERVAL:
-            self.logger.debug('Invalid update_interval {} provided. Defaulting to {}'.format(
+        if update_interval < enums.ConfigManager.MIN_UPDATE_INTERVAL:
+            self.logger.debug('update_interval value {} too small. Defaulting to {}'.format(
                 update_interval,
                 enums.ConfigManager.DEFAULT_UPDATE_INTERVAL)
             )
-            self.update_interval = enums.ConfigManager.DEFAULT_UPDATE_INTERVAL
+            update_interval = enums.ConfigManager.DEFAULT_UPDATE_INTERVAL
+
+        self.update_interval = update_interval
 
     def set_last_modified(self, response_headers):
         """ Looks up and sets last modified time based on Last-Modified header in the response.
@@ -269,9 +278,14 @@ def is_running(self):
 
     def _run(self):
         """ Triggered as part of the thread which fetches the datafile and sleeps until next update interval. """
-        while self.is_running:
-            self.fetch_datafile()
-            time.sleep(self.update_interval)
+        try:
+          while self.is_running:
+              self.fetch_datafile()
+              time.sleep(self.update_interval)
+        except (OSError, OverflowError) as err:
+            self.logger.error('Error in time.sleep. '
+                              'Provided update_interval value may be too big. Error: {}'.format(str(err)))
+            raise
 
     def start(self):
         """ Start the config manager and the thread to periodically fetch datafile. """
diff --git a/optimizely/helpers/validator.py b/optimizely/helpers/validator.py
index e08e1fd7e..c9ad2a219 100644
--- a/optimizely/helpers/validator.py
+++ b/optimizely/helpers/validator.py
@@ -221,7 +221,7 @@ def is_finite_number(value):
              greater than absolute limit of 2^53 else False.
   """
   if not isinstance(value, (numbers.Integral, float)):
-      # numbers.Integral instead of int to accomodate long integer in python 2
+      # numbers.Integral instead of int to accommodate long integer in python 2
     return False
 
   if isinstance(value, bool):
@@ -244,7 +244,7 @@ def are_values_same_type(first_val, second_val):
 
   Args:
     first_val: Value to validate.
-    second_Val: Value to validate.
+    second_val: Value to validate.
 
   Returns:
     Boolean: True if both values belong to same type. Otherwise False.
diff --git a/tests/test_config_manager.py b/tests/test_config_manager.py
index 5aafa3618..5ea73c263 100644
--- a/tests/test_config_manager.py
+++ b/tests/test_config_manager.py
@@ -188,6 +188,11 @@ def test_set_update_interval(self, _):
         """ Test set_update_interval with different inputs. """
         project_config_manager = config_manager.PollingConfigManager(sdk_key='some_key')
 
+        # Assert that if invalid update_interval is set, then exception is raised.
+        with self.assertRaisesRegexp(optimizely_exceptions.InvalidInputException,
+                                     'Invalid update_interval "invalid interval" provided.'):
+            project_config_manager.set_update_interval('invalid interval')
+
         # Assert that update_interval cannot be set to less than allowed minimum and instead is set to default value.
         project_config_manager.set_update_interval(0.42)
         self.assertEqual(enums.ConfigManager.DEFAULT_UPDATE_INTERVAL, project_config_manager.update_interval)