diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 346d10198d..68551aad51 100644
--- a/django/db/backends/__init__.py
+++ b/django/db/backends/__init__.py
@@ -269,6 +269,8 @@ class BaseDatabaseWrapper(object):
         """
         self.validate_no_atomic_block()
 
+        self.ensure_connection()
+
         self.transaction_state.append(managed)
 
         if not managed and self.is_dirty() and not forced:
@@ -286,6 +288,8 @@ class BaseDatabaseWrapper(object):
         """
         self.validate_no_atomic_block()
 
+        self.ensure_connection()
+
         if self.transaction_state:
             del self.transaction_state[-1]
         else: