diff --git a/django/conf/locale/fr_CA/formats.py b/django/conf/locale/fr_CA/formats.py
index 4f1a017f168d..ecb45f5bbb14 100644
--- a/django/conf/locale/fr_CA/formats.py
+++ b/django/conf/locale/fr_CA/formats.py
@@ -3,12 +3,12 @@
 # The *_FORMAT strings use the Django date format syntax,
 # see https://docs.djangoproject.com/en/dev/ref/templates/builtins/#date
 DATE_FORMAT = "j F Y"  # 31 janvier 2024
-TIME_FORMAT = "H\xa0h\xa0i"  # 13 h 40
-DATETIME_FORMAT = "j F Y, H\xa0h\xa0i"  # 31 janvier 2024, 13 h 40
+TIME_FORMAT = "H\xa0\\h\xa0i"  # 13 h 40
+DATETIME_FORMAT = "j F Y, H\xa0\\h\xa0i"  # 31 janvier 2024, 13 h 40
 YEAR_MONTH_FORMAT = "F Y"
 MONTH_DAY_FORMAT = "j F"
 SHORT_DATE_FORMAT = "Y-m-d"
-SHORT_DATETIME_FORMAT = "Y-m-d H\xa0h\xa0i"
+SHORT_DATETIME_FORMAT = "Y-m-d H\xa0\\h\xa0i"
 FIRST_DAY_OF_WEEK = 0  # Dimanche
 
 # The *_INPUT_FORMATS strings use the Python strftime format syntax,
diff --git a/django/db/backends/base/operations.py b/django/db/backends/base/operations.py
index 16a6296f9b5f..9822a7fbb1c8 100644
--- a/django/db/backends/base/operations.py
+++ b/django/db/backends/base/operations.py
@@ -9,6 +9,7 @@
 from django.db import NotSupportedError, transaction
 from django.db.models.expressions import Col
 from django.utils import timezone
+from django.utils.duration import duration_microseconds
 from django.utils.encoding import force_str
 
 
@@ -564,6 +565,16 @@ def adapt_datetimefield_value(self, value):
             return None
         return str(value)
 
+    def adapt_durationfield_value(self, value):
+        """
+        Transform a timedelta value into an object compatible with what is
+        expected by the backend driver for duration columns (by default,
+        an integer of microseconds).
+        """
+        if value is None:
+            return None
+        return duration_microseconds(value)
+
     def adapt_timefield_value(self, value):
         """
         Transform a time value to an object compatible with what is expected
diff --git a/django/db/backends/oracle/operations.py b/django/db/backends/oracle/operations.py
index bc152c4e6ed5..e5da5928f966 100644
--- a/django/db/backends/oracle/operations.py
+++ b/django/db/backends/oracle/operations.py
@@ -608,6 +608,9 @@ def adapt_datetimefield_value(self, value):
 
         return Oracle_datetime.from_datetime(value)
 
+    def adapt_durationfield_value(self, value):
+        return value
+
     def adapt_timefield_value(self, value):
         if value is None:
             return None
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index 7cd868d78951..91456e3dafca 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -330,6 +330,9 @@ def adapt_datefield_value(self, value):
     def adapt_datetimefield_value(self, value):
         return value
 
+    def adapt_durationfield_value(self, value):
+        return value
+
     def adapt_timefield_value(self, value):
         return value
 
diff --git a/django/db/models/deletion.py b/django/db/models/deletion.py
index b1939f8b358d..8d3fa5c92cde 100644
--- a/django/db/models/deletion.py
+++ b/django/db/models/deletion.py
@@ -309,7 +309,10 @@ def collect(
         protected_objects = defaultdict(list)
         for related in get_candidate_relations_to_delete(model._meta):
             # Preserve parent reverse relationships if keep_parents=True.
-            if keep_parents and related.model in model._meta.all_parents:
+            if (
+                keep_parents
+                and related.model._meta.concrete_model in model._meta.all_parents
+            ):
                 continue
             field = related.field
             on_delete = field.remote_field.on_delete
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index ee7a30cc303e..f12ae97968ea 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -30,7 +30,7 @@
     parse_duration,
     parse_time,
 )
-from django.utils.duration import duration_microseconds, duration_string
+from django.utils.duration import duration_string
 from django.utils.functional import Promise, cached_property
 from django.utils.ipv6 import MAX_IPV6_ADDRESS_LENGTH, clean_ipv6_address
 from django.utils.text import capfirst
@@ -1890,11 +1890,7 @@ def to_python(self, value):
         )
 
     def get_db_prep_value(self, value, connection, prepared=False):
-        if connection.features.has_native_duration_field:
-            return value
-        if value is None:
-            return None
-        return duration_microseconds(value)
+        return connection.ops.adapt_durationfield_value(value)
 
     def get_db_converters(self, connection):
         converters = []
diff --git a/docs/ref/contrib/postgres/search.txt b/docs/ref/contrib/postgres/search.txt
index 88e3cfaeb045..0d14bc8c0588 100644
--- a/docs/ref/contrib/postgres/search.txt
+++ b/docs/ref/contrib/postgres/search.txt
@@ -27,7 +27,7 @@ single column in the database. For example:
 .. code-block:: pycon
 
     >>> Entry.objects.filter(body_text__search="Cheese")
-    [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]
+    <QuerySet [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]>
 
 This creates a ``to_tsvector`` in the database from the ``body_text`` field
 and a ``plainto_tsquery`` from the search term ``'Cheese'``, both using the
@@ -52,7 +52,7 @@ To query against both fields, use a ``SearchVector``:
     >>> Entry.objects.annotate(
     ...     search=SearchVector("body_text", "blog__tagline"),
     ... ).filter(search="Cheese")
-    [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]
+    <QuerySet [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]>
 
 The arguments to ``SearchVector`` can be any
 :class:`~django.db.models.Expression` or the name of a field. Multiple
@@ -67,7 +67,7 @@ For example:
     >>> Entry.objects.annotate(
     ...     search=SearchVector("body_text") + SearchVector("blog__tagline"),
     ... ).filter(search="Cheese")
-    [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]
+    <QuerySet [<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]>
 
 See :ref:`postgresql-fts-search-configuration` and
 :ref:`postgresql-fts-weighting-queries` for an explanation of the ``config``
@@ -142,7 +142,7 @@ order by relevancy:
     >>> vector = SearchVector("body_text")
     >>> query = SearchQuery("cheese")
     >>> Entry.objects.annotate(rank=SearchRank(vector, query)).order_by("-rank")
-    [<Entry: Cheese on Toast recipes>, <Entry: Pizza recipes>]
+    <QuerySet [<Entry: Cheese on Toast recipes>, <Entry: Pizza recipes>]>
 
 See :ref:`postgresql-fts-weighting-queries` for an explanation of the
 ``weights`` parameter.
@@ -240,7 +240,7 @@ different language parsers and dictionaries as defined by the database:
     >>> Entry.objects.annotate(
     ...     search=SearchVector("body_text", config="french"),
     ... ).filter(search=SearchQuery("œuf", config="french"))
-    [<Entry: Pain perdu>]
+    <QuerySet [<Entry: Pain perdu>]>
 
 The value of ``config`` could also be stored in another column:
 
@@ -250,7 +250,7 @@ The value of ``config`` could also be stored in another column:
     >>> Entry.objects.annotate(
     ...     search=SearchVector("body_text", config=F("blog__language")),
     ... ).filter(search=SearchQuery("œuf", config=F("blog__language")))
-    [<Entry: Pain perdu>]
+    <QuerySet [<Entry: Pain perdu>]>
 
 .. _postgresql-fts-weighting-queries:
 
@@ -364,7 +364,7 @@ if it were an annotated ``SearchVector``:
 
     >>> Entry.objects.update(search_vector=SearchVector("body_text"))
     >>> Entry.objects.filter(search_vector="cheese")
-    [<Entry: Cheese on Toast recipes>, <Entry: Pizza recipes>]
+    <QuerySet [<Entry: Cheese on Toast recipes>, <Entry: Pizza recipes>]>
 
 .. _PostgreSQL documentation: https://www.postgresql.org/docs/current/textsearch-features.html#TEXTSEARCH-UPDATE-TRIGGERS
 
@@ -403,7 +403,7 @@ Usage example:
     ... ).filter(
     ...     similarity__gt=0.3
     ... ).order_by("-similarity")
-    [<Author: Katy Stevens>, <Author: Stephen Keats>]
+    <QuerySet [<Author: Katy Stevens>, <Author: Stephen Keats>]>
 
 ``TrigramWordSimilarity``
 -------------------------
@@ -426,7 +426,7 @@ Usage example:
     ... ).filter(
     ...     similarity__gt=0.3
     ... ).order_by("-similarity")
-    [<Author: Katy Stevens>]
+    <QuerySet [<Author: Katy Stevens>]>
 
 ``TrigramStrictWordSimilarity``
 -------------------------------
@@ -459,7 +459,7 @@ Usage example:
     ... ).filter(
     ...     distance__lte=0.7
     ... ).order_by("distance")
-    [<Author: Katy Stevens>, <Author: Stephen Keats>]
+    <QuerySet [<Author: Katy Stevens>, <Author: Stephen Keats>]>
 
 ``TrigramWordDistance``
 -----------------------
@@ -482,7 +482,7 @@ Usage example:
     ... ).filter(
     ...     distance__lte=0.7
     ... ).order_by("distance")
-    [<Author: Katy Stevens>]
+    <QuerySet [<Author: Katy Stevens>]>
 
 ``TrigramStrictWordDistance``
 -----------------------------
diff --git a/docs/releases/6.1.txt b/docs/releases/6.1.txt
index be05350d94d8..edfdacf6b7a7 100644
--- a/docs/releases/6.1.txt
+++ b/docs/releases/6.1.txt
@@ -243,7 +243,9 @@ Database backend API
 This section describes changes that may be needed in third-party database
 backends.
 
-* ...
+* The ``DatabaseOperations.adapt_durationfield_value()`` hook is added. If the
+  database has native support for ``DurationField``, override this method to
+  simply return the value.
 
 Miscellaneous
 -------------
diff --git a/tests/delete/models.py b/tests/delete/models.py
index 4b627712bb65..7f123b339698 100644
--- a/tests/delete/models.py
+++ b/tests/delete/models.py
@@ -32,6 +32,11 @@ class RChild(R):
     pass
 
 
+class RProxy(R):
+    class Meta:
+        proxy = True
+
+
 class RChildChild(RChild):
     pass
 
@@ -179,7 +184,7 @@ class RelToBase(models.Model):
 
 
 class Origin(models.Model):
-    pass
+    r_proxy = models.ForeignKey("RProxy", models.CASCADE, null=True)
 
 
 class Referrer(models.Model):
diff --git a/tests/delete/tests.py b/tests/delete/tests.py
index 7b9dcdb079b5..59140b5c621f 100644
--- a/tests/delete/tests.py
+++ b/tests/delete/tests.py
@@ -34,6 +34,7 @@
     RChild,
     RChildChild,
     Referrer,
+    RProxy,
     S,
     T,
     User,
@@ -675,6 +676,14 @@ def receiver(instance, **kwargs):
                 )
                 signal.disconnect(receiver, sender=Referrer)
 
+    def test_keep_parents_does_not_delete_proxy_related(self):
+        r_child = RChild.objects.create()
+        r_proxy = RProxy.objects.get(pk=r_child.pk)
+        Origin.objects.create(r_proxy=r_proxy)
+        self.assertEqual(Origin.objects.count(), 1)
+        r_child.delete(keep_parents=True)
+        self.assertEqual(Origin.objects.count(), 1)
+
 
 class FastDeleteTests(TestCase):
     def test_fast_delete_all(self):
diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
index b4bdf160d6f8..aac56f5df451 100644
--- a/tests/i18n/tests.py
+++ b/tests/i18n/tests.py
@@ -1158,6 +1158,27 @@ def test_l10n_enabled(self):
                 ),
             )
 
+    def test_uncommon_locale_formats(self):
+        testcases = {
+            # French Canadian locale uses 'h' as time format seperator.
+            ("fr-ca", time_format, (self.t, "TIME_FORMAT")): "10\xa0h\xa015",
+            (
+                "fr-ca",
+                date_format,
+                (self.dt, "DATETIME_FORMAT"),
+            ): "31 décembre 2009, 20\xa0h\xa050",
+            (
+                "fr-ca",
+                date_format,
+                (self.dt, "SHORT_DATETIME_FORMAT"),
+            ): "2009-12-31 20\xa0h\xa050",
+        }
+        for testcase, expected in testcases.items():
+            locale, format_function, format_args = testcase
+            with self.subTest(locale=locale, expected=expected):
+                with translation.override(locale, deactivate=True):
+                    self.assertEqual(expected, format_function(*format_args))
+
     def test_sub_locales(self):
         """
         Check if sublocales fall back to the main locale