Fixed #32915 - Don't catch ImportErrors unless it's the settings module that can't be imported

Based on work by Rohith PR and others in PR #14622

django/conf/__init__.py

@@ -163,7 +163,13 @@ class Settings:
         # store the settings module in case someone later cares
         self.SETTINGS_MODULE = settings_module
 
-        mod = importlib.import_module(self.SETTINGS_MODULE)
+        try:
+            mod = importlib.import_module(self.SETTINGS_MODULE)
+        except ImportError as exc:
+            # If the settings module cannot be imported, treat it as a configuration error.
+            if exc.name == self.SETTINGS_MODULE:
+                raise ImproperlyConfigured(f"Settings module {self.SETTINGS_MODULE} could not be imported") from exc
+            raise
 
         tuple_settings = (
             "ALLOWED_HOSTS",

django/core/management/__init__.py

@@ -382,7 +382,9 @@ class ManagementUtility:
             settings.INSTALLED_APPS
         except ImproperlyConfigured as exc:
             self.settings_exception = exc
-        except ImportError as exc:
+            # The following commands can be run even without a valid settings file configured
+            if subcommand not in {'startproject', 'startapp', 'makemessages'}:
+                sys.stderr.write(str(exc) + '\n')
             self.settings_exception = exc
 
         if settings.configured:

tests/admin_scripts/tests.py

@@ -1412,12 +1412,12 @@ class ManageSettingsWithSettingsErrors(AdminScriptTestCase):
         self.write_settings(
             "settings.py",
             extra="from django.core.exceptions import ImproperlyConfigured\n"
-            "raise ImproperlyConfigured()",
+            "raise ImproperlyConfigured('Improper configuration')",
         )
         args = ["help"]
         out, err = self.run_manage(args)
         self.assertOutput(out, "only Django core commands are listed")
-        self.assertNoOutput(err)
+        self.assertOutput(err, "Improper configuration")
 
 
 class ManageCheck(AdminScriptTestCase):

tests/settings_tests/tests.py

@@ -338,6 +338,20 @@ class SettingsTests(SimpleTestCase):
         with self.assertRaisesMessage(ValueError, "Incorrect timezone setting: test"):
             settings._setup()
 
+    def test_unable_to_import_settings_module(self):
+        with self.assertRaisesMessage(
+            ImproperlyConfigured, "Settings module fake_settings_module could not be imported"
+        ):
+            Settings('fake_settings_module')
+
+    def test_unable_to_import_a_random_module(self):
+        def mock_import_module(_):
+            raise ModuleNotFoundError("No module named 'fake_module'", name="fake_module")
+
+        with mock.patch("importlib.import_module", mock_import_module):
+            with self.assertRaisesMessage(ImportError, "No module named 'fake_module'"):
+                Settings('fake_settings_module')
+
 
 class TestComplexSettingOverride(SimpleTestCase):
     def setUp(self):