diff --git a/django/db/backends/postgresql_psycopg2/base.py b/django/db/backends/postgresql_psycopg2/base.py
index a76ca3c0df..e625c28ae4 100644
--- a/django/db/backends/postgresql_psycopg2/base.py
+++ b/django/db/backends/postgresql_psycopg2/base.py
@@ -198,7 +198,7 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         tz = self.settings_dict['TIME_ZONE']
         conn_tz = self.connection.get_parameter_status('TimeZone')
 
-        if conn_tz != tz:
+        if tz and conn_tz != tz:
             cursor = self.connection.cursor()
             try:
                 cursor.execute(self.ops.set_time_zone_sql(), [tz])
diff --git a/django/test/signals.py b/django/test/signals.py
index 0c2bf5201c..fd3de51f2c 100644
--- a/django/test/signals.py
+++ b/django/test/signals.py
@@ -73,7 +73,7 @@ def update_connections_time_zone(**kwargs):
     for conn in connections.all():
         conn.settings_dict['TIME_ZONE'] = tz
         tz_sql = conn.ops.set_time_zone_sql()
-        if tz_sql:
+        if tz_sql and tz:
             conn.cursor().execute(tz_sql, [tz])
 
 
diff --git a/docs/releases/1.8.10.txt b/docs/releases/1.8.10.txt
index d680bad687..c9e77552e6 100644
--- a/docs/releases/1.8.10.txt
+++ b/docs/releases/1.8.10.txt
@@ -9,4 +9,5 @@ Django 1.8.10 fixes several bugs in 1.8.9.
 Bugfixes
 ========
 
-* ...
+* Fixed a crash on PostgreSQL that prevented using ``TIME_ZONE=None`` and
+  ``USE_TZ=False`` (:ticket:`26177`).
diff --git a/tests/backends/tests.py b/tests/backends/tests.py
index e4b277a95a..a645d9f23e 100644
--- a/tests/backends/tests.py
+++ b/tests/backends/tests.py
@@ -804,6 +804,11 @@ class BackendTestCase(TransactionTestCase):
             BaseDatabaseWrapper.queries_limit = old_queries_limit
             new_connection.close()
 
+    def test_timezone_none_use_tz_false(self):
+        connection.ensure_connection()
+        with self.settings(TIME_ZONE=None, USE_TZ=False):
+            connection.init_connection_state()
+
 
 # We don't make these tests conditional because that means we would need to
 # check and differentiate between: