Refs #23524 -- Unified BaseDatabaseWrapper.timezone.

There was a special case in this property to return None when the
database backend supports time zone. However, only the PostgreSQL
backend supports time zones and it never uses this property.

django/db/backends/base/base.py

@@ -117,18 +117,21 @@ class BaseDatabaseWrapper:
     @cached_property
     def timezone(self):
         """
-        Time zone for datetimes stored as naive values in the database.
+        Return a tzinfo of the database connection time zone.
 
-        Return a tzinfo object or None.
+        This is only used when time zone support is enabled. When a datetime is
+        read from the database, it is always returned in this time zone.
 
-        This is only needed when time zone support is enabled and the database
-        doesn't support time zones. (When the database supports time zones,
-        the adapter handles aware datetimes so Django doesn't need to.)
+        When the database backend supports time zones, it doesn't matter which
+        time zone Django uses, as long as aware datetimes are used everywhere.
+        For simplicity, Django selects UTC.
+
+        When the database backend doesn't support time zones, the time zone
+        Django uses can be selected with the TIME_ZONE configuration option, so
+        it can match what other users of the database expect.
         """
         if not settings.USE_TZ:
             return None
-        elif self.features.supports_timezones:
-            return None
         elif self.settings_dict['TIME_ZONE'] is None:
             return timezone.utc
         else:

docs/releases/3.1.txt

@@ -297,6 +297,11 @@ backends.
 * ``DatabaseOperations.fetch_returned_insert_columns()`` now requires an
   additional ``returning_params`` argument.
 
+* ``connection.timezone`` property is now ``'UTC'`` by default, or the
+  :setting:`TIME_ZONE <DATABASE-TIME_ZONE>` when :setting:`USE_TZ` is ``True``
+  on databases that support time zones. Previously, it was ``None`` on
+  databases that support time zones.
+
 Dropped support for MariaDB 10.1
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