Improved error message in SQLite `DatabaseOperations.check_expression_support()`.

2 files changed, 11 insertions, 7 deletions

diff --git a/django/db/backends/sqlite3/operations.py b/django/db/backends/sqlite3/operations.py
index 33a39239ca..949cbd4ff9 100644
--- a/django/db/backends/sqlite3/operations.py
+++ b/django/db/backends/sqlite3/operations.py
@@ -48,10 +48,10 @@ class DatabaseOperations(BaseDatabaseOperations):
                     pass
                 else:
                     if isinstance(output_field, DATETIME_FIELDS):
+                        klass = expression.__class__.__name__
                         raise NotSupportedError(
-                            "You cannot use Sum, Avg, StdDev, and Variance "
-                            "aggregations on date/time fields in sqlite3 "
-                            "since date/time is saved as text."
+                            f"SQLite does not support {klass} on date or time "
+                            "fields, because they are stored as text."
                         )
         if (
             isinstance(expression, models.Aggregate)
diff --git a/tests/backends/sqlite/tests.py b/tests/backends/sqlite/tests.py
index 34c0eca0ff..f47e96be4e 100644
--- a/tests/backends/sqlite/tests.py
+++ b/tests/backends/sqlite/tests.py
@@ -31,13 +31,17 @@ class Tests(TestCase):
     def test_aggregation(self):
         """Raise NotSupportedError when aggregating on date/time fields."""
         for aggregate in (Sum, Avg, Variance, StdDev):
-            with self.assertRaises(NotSupportedError):
+            msg = (
+                f"SQLite does not support {aggregate.__name__} on date or "
+                "time fields, because they are stored as text."
+            )
+            with self.assertRaisesMessage(NotSupportedError, msg):
                 Item.objects.aggregate(aggregate("time"))
-            with self.assertRaises(NotSupportedError):
+            with self.assertRaisesMessage(NotSupportedError, msg):
                 Item.objects.aggregate(aggregate("date"))
-            with self.assertRaises(NotSupportedError):
+            with self.assertRaisesMessage(NotSupportedError, msg):
                 Item.objects.aggregate(aggregate("last_modified"))
-            with self.assertRaises(NotSupportedError):
+            with self.assertRaisesMessage(NotSupportedError, msg):
                 Item.objects.aggregate(
                     **{
                         "complex": aggregate("last_modified")