diff --git a/corporate/lib/stripe.py b/corporate/lib/stripe.py
index c670e698d2..3ab4917dd1 100644
--- a/corporate/lib/stripe.py
+++ b/corporate/lib/stripe.py
@@ -504,7 +504,9 @@ def make_end_of_cycle_updates_if_needed(
             standard_plan_last_ledger = (
                 LicenseLedger.objects.filter(plan=standard_plan).order_by("id").last()
             )
+            assert standard_plan_last_ledger is not None
             licenses_for_plus_plan = standard_plan_last_ledger.licenses_at_next_renewal
+            assert licenses_for_plus_plan is not None
             plus_plan_ledger_entry = LicenseLedger.objects.create(
                 plan=plus_plan,
                 is_renewal=True,
@@ -1040,6 +1042,7 @@ def estimate_annual_recurring_revenue_by_realm() -> Dict[str, int]:  # nocoverag
         if plan.billing_schedule == CustomerPlan.MONTHLY:
             renewal_cents *= 12
         # TODO: Decimal stuff
+        assert plan.customer.realm is not None
         annual_revenue[plan.customer.realm.string_id] = int(renewal_cents / 100)
     return annual_revenue
 
@@ -1048,6 +1051,7 @@ def get_realms_to_default_discount_dict() -> Dict[str, Decimal]:
     realms_to_default_discount: Dict[str, Any] = {}
     customers = Customer.objects.exclude(default_discount=None).exclude(default_discount=0)
     for customer in customers:
+        assert customer.realm is not None
         realms_to_default_discount[customer.realm.string_id] = assert_is_not_none(
             customer.default_discount
         )
@@ -1116,6 +1120,7 @@ def downgrade_small_realms_behind_on_payments_as_needed() -> None:
     customers = Customer.objects.all().exclude(stripe_customer_id=None)
     for customer in customers:
         realm = customer.realm
+        assert realm is not None
 
         # For larger realms, we generally want to talk to the customer
         # before downgrading or cancelling invoices; so this logic only applies with 5.
@@ -1172,6 +1177,7 @@ def switch_realm_from_standard_to_plus_plan(realm: Realm) -> None:
     standard_plan_last_renewal_ledger = (
         LicenseLedger.objects.filter(is_renewal=True, plan=standard_plan).order_by("id").last()
     )
+    assert standard_plan_last_renewal_ledger is not None
     standard_plan_last_renewal_amount = (
         standard_plan_last_renewal_ledger.licenses * standard_plan.price_per_license
     )
diff --git a/corporate/tests/test_stripe.py b/corporate/tests/test_stripe.py
index 8d38f4667e..aa85c08a16 100644
--- a/corporate/tests/test_stripe.py
+++ b/corporate/tests/test_stripe.py
@@ -583,10 +583,12 @@ class StripeTestCase(ZulipTestCase):
             else:
                 expected_session_details["type"] = "free_trial_upgrade_from_billing_page"
         else:
+            last_stripe_payment_intent = PaymentIntent.objects.last()
+            assert last_stripe_payment_intent is not None
             expected_session_details["type"] = "upgrade_from_billing_page"
             expected_session_details[
                 "stripe_payment_intent_id"
-            ] = PaymentIntent.objects.last().stripe_payment_intent_id
+            ] = last_stripe_payment_intent.stripe_payment_intent_id
 
         self.assert_details_of_valid_session_from_event_status_endpoint(
             upgrade_json_response.json()["stripe_session_id"], expected_session_details
diff --git a/zerver/lib/import_realm.py b/zerver/lib/import_realm.py
index 3d06521780..727ba7b4a6 100644
--- a/zerver/lib/import_realm.py
+++ b/zerver/lib/import_realm.py
@@ -1029,6 +1029,7 @@ def do_import_realm(import_dir: Path, subdomain: str, processes: int = 1) -> Rea
     )
     for realm_emoji in RealmEmoji.objects.filter(realm=realm):
         if realm_emoji.author_id is None:
+            assert first_user_profile is not None
             realm_emoji.author_id = first_user_profile.id
             realm_emoji.save(update_fields=["author_id"])
 
diff --git a/zerver/tests/test_email_mirror.py b/zerver/tests/test_email_mirror.py
index ef495db19c..c61e8560ca 100644
--- a/zerver/tests/test_email_mirror.py
+++ b/zerver/tests/test_email_mirror.py
@@ -567,6 +567,7 @@ class TestEmailMirrorMessagesWithAttachments(ZulipTestCase):
 
         message = most_recent_message(user_profile)
         attachment = Attachment.objects.last()
+        assert attachment is not None
         self.assertEqual(list(attachment.messages.values_list("id", flat=True)), [message.id])
         self.assertEqual(
             message.sender, get_system_bot(settings.EMAIL_GATEWAY_BOT, stream.realm_id)
diff --git a/zerver/tests/test_email_notifications.py b/zerver/tests/test_email_notifications.py
index fc2e183c8e..899662d22c 100644
--- a/zerver/tests/test_email_notifications.py
+++ b/zerver/tests/test_email_notifications.py
@@ -338,6 +338,7 @@ class TestFollowupEmails(ZulipTestCase):
         cordelia = self.example_user("cordelia")
         enqueue_welcome_emails(self.example_user("cordelia"), realm_creation=True)
         scheduled_email = ScheduledEmail.objects.filter(users=cordelia).last()
+        assert scheduled_email is not None
         self.assertEqual(
             orjson.loads(scheduled_email.data)["template_prefix"], "zerver/emails/followup_day1"
         )
@@ -359,6 +360,7 @@ class TestFollowupEmails(ZulipTestCase):
         cordelia.realm.save()
         enqueue_welcome_emails(self.example_user("cordelia"), realm_creation=True)
         scheduled_email = ScheduledEmail.objects.filter(users=cordelia).last()
+        assert scheduled_email is not None
         self.assertEqual(
             orjson.loads(scheduled_email.data)["template_prefix"], "zerver/emails/followup_day1"
         )
diff --git a/zerver/tests/test_import_export.py b/zerver/tests/test_import_export.py
index 0ce846004c..d4e13a09c6 100644
--- a/zerver/tests/test_import_export.py
+++ b/zerver/tests/test_import_export.py
@@ -223,6 +223,7 @@ class ExportFile(ZulipTestCase):
 
         realm_emoji = RealmEmoji.objects.get(author=user)
         file_name = realm_emoji.file_name
+        assert file_name is not None
         assert file_name.endswith(".png")
 
         emoji_path = f"{realm.id}/emoji/images/{file_name}"
@@ -510,6 +511,7 @@ class RealmImportExportTest(ExportFile):
             content="Thumbs up for export",
         )
         message = Message.objects.last()
+        assert message is not None
         consented_user_ids = [self.example_user(user).id for user in ["iago", "hamlet"]]
         do_add_reaction(
             self.example_user("iago"), message, "outbox", "1f4e4", Reaction.UNICODE_EMOJI
@@ -1517,10 +1519,10 @@ class SingleUserExportTest(ExportFile):
             reaction_type=None,
         )
         reaction = Reaction.objects.order_by("id").last()
-        assert reaction
 
         @checker
         def zerver_reaction(records: List[Record]) -> None:
+            assert reaction
             (exported_reaction,) = records
             self.assertEqual(
                 exported_reaction,
diff --git a/zerver/tests/test_link_embed.py b/zerver/tests/test_link_embed.py
index 1e0fa4f4ba..284c835c56 100644
--- a/zerver/tests/test_link_embed.py
+++ b/zerver/tests/test_link_embed.py
@@ -373,6 +373,7 @@ class PreviewTestCase(ZulipTestCase):
 
         embedded_link = f'<a href="{url}" title="The Rock">The Rock</a>'
         msg = Message.objects.select_related("sender").get(id=msg_id)
+        assert msg.rendered_content is not None
         self.assertIn(embedded_link, msg.rendered_content)
 
     @responses.activate
@@ -462,6 +463,7 @@ class PreviewTestCase(ZulipTestCase):
                     # up-to-date event for edited_url.
                     queue_json_publish(*args, **kwargs)
                     msg = Message.objects.select_related("sender").get(id=msg_id)
+                    assert msg.rendered_content is not None
                     self.assertIn(
                         f'<a href="{edited_url}" title="The Rock">The Rock</a>',
                         msg.rendered_content,
@@ -821,6 +823,7 @@ class PreviewTestCase(ZulipTestCase):
 
         assert cached_data is not None
         msg = Message.objects.select_related("sender").get(id=msg_id)
+        assert msg.rendered_content is not None
         self.assertIn(cached_data.title, msg.rendered_content)
         assert cached_data.image is not None
         self.assertIn(re.sub(r"([^\w-])", r"\\\1", cached_data.image), msg.rendered_content)
@@ -946,6 +949,7 @@ class PreviewTestCase(ZulipTestCase):
 
         self.assertEqual(cached_data, mocked_data)
         msg.refresh_from_db()
+        assert msg.rendered_content is not None
         self.assertIn(f'a data-id="{escape(mocked_data.html)}"', msg.rendered_content)
 
     @responses.activate
diff --git a/zerver/tests/test_markdown.py b/zerver/tests/test_markdown.py
index 0d172d1d2e..3c920bf94c 100644
--- a/zerver/tests/test_markdown.py
+++ b/zerver/tests/test_markdown.py
@@ -1195,6 +1195,7 @@ class MarkdownTest(ZulipTestCase):
         realm_emoji = RealmEmoji.objects.filter(
             realm=realm, name="green_tick", deactivated=False
         ).get()
+        assert realm_emoji.file_name is not None
         self.assertEqual(
             converted.rendered_content,
             "<p>{}</p>".format(emoji_img(":green_tick:", realm_emoji.file_name, realm.id)),
diff --git a/zerver/tests/test_message_edit.py b/zerver/tests/test_message_edit.py
index ac21a480b5..1c9f294574 100644
--- a/zerver/tests/test_message_edit.py
+++ b/zerver/tests/test_message_edit.py
@@ -28,6 +28,7 @@ from zerver.lib.user_topics import (
     set_topic_mutes,
     topic_is_muted,
 )
+from zerver.lib.utils import assert_is_not_none
 from zerver.models import Message, Realm, Stream, UserMessage, UserProfile, get_realm, get_stream
 
 
@@ -767,7 +768,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_content"], "content 1")
         self.assertEqual(history[0]["user_id"], hamlet.id)
         self.assertEqual(
@@ -788,7 +789,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_topic"], "topic 1")
         self.assertEqual(history[0]["topic"], "topic 2")
         self.assertEqual(history[0]["user_id"], hamlet.id)
@@ -805,7 +806,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_stream"], stream_1.id)
         self.assertEqual(history[0]["stream"], stream_2.id)
         self.assertEqual(history[0]["user_id"], self.example_user("iago").id)
@@ -820,7 +821,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_content"], "content 2")
         self.assertEqual(history[0]["prev_topic"], "topic 2")
         self.assertEqual(history[0]["topic"], "topic 3")
@@ -845,7 +846,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_content"], "content 3")
         self.assertEqual(history[0]["user_id"], hamlet.id)
 
@@ -858,7 +859,7 @@ class EditMessageTest(EditMessageTestCase):
             },
         )
         self.assert_json_success(result)
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
         self.assertEqual(history[0]["prev_topic"], "topic 3")
         self.assertEqual(history[0]["topic"], "topic 4")
         self.assertEqual(history[0]["prev_stream"], stream_2.id)
@@ -878,7 +879,7 @@ class EditMessageTest(EditMessageTestCase):
 
         # Now, we verify that all of the edits stored in the message.edit_history
         # have the correct data structure
-        history = orjson.loads(Message.objects.get(id=msg_id).edit_history)
+        history = orjson.loads(assert_is_not_none(Message.objects.get(id=msg_id).edit_history))
 
         self.assertEqual(history[0]["prev_topic"], "topic 3")
         self.assertEqual(history[0]["topic"], "topic 4")
@@ -1588,7 +1589,9 @@ class EditMessageTest(EditMessageTestCase):
                 # Since edit history is being generated by do_update_message,
                 # it's contents can vary over time; So, to keep this test
                 # future proof, we only verify it's length.
-                self.assert_length(orjson.loads(msg.edit_history), len_edit_history)
+                self.assert_length(
+                    orjson.loads(assert_is_not_none(msg.edit_history)), len_edit_history
+                )
 
             for msg_id in [id3, id4]:
                 msg = Message.objects.get(id=msg_id)
@@ -1642,18 +1645,20 @@ class EditMessageTest(EditMessageTestCase):
         msg2 = Message.objects.get(id=id2)
         msg3 = Message.objects.get(id=id3)
 
-        msg1_edit_history = orjson.loads(msg1.edit_history)
+        msg1_edit_history = orjson.loads(assert_is_not_none(msg1.edit_history))
         self.assertTrue("prev_content" in msg1_edit_history[0].keys())
 
         for msg in [msg2, msg3]:
-            self.assertFalse("prev_content" in orjson.loads(msg.edit_history)[0].keys())
+            self.assertFalse(
+                "prev_content" in orjson.loads(assert_is_not_none(msg.edit_history))[0].keys()
+            )
 
         for msg in [msg1, msg2, msg3]:
             self.assertEqual(
                 new_topic,
                 msg.topic_name(),
             )
-            self.assert_length(orjson.loads(msg.edit_history), 1)
+            self.assert_length(orjson.loads(assert_is_not_none(msg.edit_history)), 1)
 
     def test_propagate_topic_forward(self) -> None:
         self.login("hamlet")
diff --git a/zerver/tests/test_scim.py b/zerver/tests/test_scim.py
index 0a6d6c43dc..94ca9c5776 100644
--- a/zerver/tests/test_scim.py
+++ b/zerver/tests/test_scim.py
@@ -287,6 +287,7 @@ class TestSCIMUser(SCIMTestCase):
         self.assertEqual(new_user_count, original_user_count + 1)
 
         new_user = UserProfile.objects.last()
+        assert new_user is not None
         self.assertEqual(new_user.delivery_email, "newuser@zulip.com")
         self.assertEqual(new_user.full_name, "New User")
 
@@ -315,6 +316,7 @@ class TestSCIMUser(SCIMTestCase):
         self.assertEqual(new_user_count, original_user_count + 1)
 
         new_user = UserProfile.objects.last()
+        assert new_user is not None
         self.assertEqual(new_user.delivery_email, "newuser@zulip.com")
         self.assertEqual(new_user.full_name, "New User")