diff --git a/openwisp_controller/config/templates/admin/config/device/change_form.html b/openwisp_controller/config/templates/admin/config/device/change_form.html
index e97999f75..cad348ad9 100644
--- a/openwisp_controller/config/templates/admin/config/device/change_form.html
+++ b/openwisp_controller/config/templates/admin/config/device/change_form.html
@@ -17,7 +17,7 @@
     the change form.
 
     We utilize a distinct form element (id="act_deact_device_form")
-    specifically for these actions. The form attribute of the submit buttons (Acivate/Deactivate)
+    specifically for these actions. The form attribute of the submit buttons (Activate/Deactivate)
     within the submit-row div references this form. By doing so, we ensure that
     these actions can be submitted independently without causing any
     disruption to the device form.
diff --git a/openwisp_controller/config/tests/test_admin.py b/openwisp_controller/config/tests/test_admin.py
index 90bca8a8a..ef36d7dae 100644
--- a/openwisp_controller/config/tests/test_admin.py
+++ b/openwisp_controller/config/tests/test_admin.py
@@ -1317,7 +1317,7 @@ def test_variable_usage(self):
 
     def test_preview_device_config_empty_id(self):
         path = reverse(f"admin:{self.app_label}_device_preview")
-        config = json.dumps({"general": {"descripion": "id: {{ id }}"}})
+        config = json.dumps({"general": {"description": "id: {{ id }}"}})
         data = {
             "id": "",
             "name": "test-empty-id",
diff --git a/openwisp_controller/config/tests/test_config.py b/openwisp_controller/config/tests/test_config.py
index cda1ad2f9..0d3f6772e 100644
--- a/openwisp_controller/config/tests/test_config.py
+++ b/openwisp_controller/config/tests/test_config.py
@@ -111,7 +111,7 @@ def test_backend_openwrt_different_versions(self):
             self.assertIsInstance(c.backend_instance, OpenWrt)
             self.assertEqual(c.backend_instance.dsa, True)
 
-        with self.subTest("DSA disabed OpenWrt Firmware"):
+        with self.subTest("DSA disabled OpenWrt Firmware"):
             c = Config(
                 backend="netjsonconfig.OpenWrt",
                 device=Device(name="test", os="OpenWrt 19.02.2 r16495-bf0c965af0"),
diff --git a/openwisp_controller/config/tests/test_selenium.py b/openwisp_controller/config/tests/test_selenium.py
index 4322c00c5..dbb09e899 100644
--- a/openwisp_controller/config/tests/test_selenium.py
+++ b/openwisp_controller/config/tests/test_selenium.py
@@ -327,7 +327,7 @@ def test_force_delete_device_with_deactivating_config(self):
             By.CSS_SELECTOR, "#deactivating-warning .messagelist .warning p"
         )
         self.find_element(by=By.CSS_SELECTOR, value="#warning-ack").click()
-        # After accepting the warning, wee need to wait for the animation
+        # After accepting the warning, we need to wait for the animation
         # to complete before trying to interact with the button,
         # otherwise the test may fail due to the button not being fully
         # visible or clickable yet.
@@ -364,7 +364,7 @@ def test_force_delete_multiple_devices_with_deactivating_config(self):
             By.CSS_SELECTOR, "#deactivating-warning .messagelist .warning p"
         )
         self.find_element(by=By.CSS_SELECTOR, value="#warning-ack").click()
-        # After accepting the warning, wee need to wait for the animation
+        # After accepting the warning, we need to wait for the animation
         # to complete before trying to interact with the button,
         # otherwise the test may fail due to the button not being fully
         # visible or clickable yet.
@@ -630,7 +630,15 @@ def get_chrome_webdriver(cls):
         return webdriver.Chrome(options=options)
 
     def _is_unsaved_changes_alert_present(self):
-        for entry in self.get_browser_logs():
+        alert = self.web_driver.execute_script(
+            "var alert = sessionStorage.getItem('unsaved_changes_alert');"
+            "sessionStorage.removeItem('unsaved_changes_alert');"
+            "return alert;"
+        )
+        if alert and "You haven't saved your changes yet!" in alert:
+            return True
+
+        for entry in self.get_browser_logs() or []:
             if (
                 entry["level"] == "WARNING"
                 and "You haven't saved your changes yet!" in entry["message"]
@@ -641,6 +649,7 @@ def _is_unsaved_changes_alert_present(self):
     def _override_unsaved_changes_alert(self):
         self.web_driver.execute_script(
             'django.jQuery(window).on("beforeunload", function(e) {'
+            " sessionStorage.setItem('unsaved_changes_alert', e.returnValue);"
             " console.warn(e.returnValue); });"
         )
 
diff --git a/openwisp_controller/config/tests/test_views.py b/openwisp_controller/config/tests/test_views.py
index fb6c1e5a3..91585a999 100644
--- a/openwisp_controller/config/tests/test_views.py
+++ b/openwisp_controller/config/tests/test_views.py
@@ -305,7 +305,7 @@ def test_get_default_values_authorization(self):
 
     def test_get_default_values_same_keys(self):
         self._login()
-        # Atleast 4 templates are required to create enough entropy in database
+        # At least 4 templates are required to create enough entropy in database
         # to make the test fail consistently without patch
         template1 = self._create_template(name="VNI 1", default_values={"vn1": "1"})
         template2 = self._create_template(
diff --git a/openwisp_controller/config/whois/tests/tests.py b/openwisp_controller/config/whois/tests/tests.py
index fd8b73fc5..275e74108 100644
--- a/openwisp_controller/config/whois/tests/tests.py
+++ b/openwisp_controller/config/whois/tests/tests.py
@@ -1178,7 +1178,7 @@ class TestWHOISSelenium(CreateWHOISMixin, SeleniumTestMixin, StaticLiveServerTes
     def test_whois_device_admin(self):
         def _assert_no_js_errors():
             browser_logs = []
-            for log in self.get_browser_logs():
+            for log in self.get_browser_logs() or []:
                 if self.browser == "chrome" and log["source"] != "console-api":
                     continue
                 elif log["message"] in ["wrong event specified: touchleave"]:
diff --git a/openwisp_controller/connection/base/models.py b/openwisp_controller/connection/base/models.py
index c79484964..17a06f7bb 100644
--- a/openwisp_controller/connection/base/models.py
+++ b/openwisp_controller/connection/base/models.py
@@ -107,7 +107,7 @@ class AbstractCredentials(ConnectorMixin, ShareableOrgMixinUniqueName, BaseModel
     """
 
     # Controls the number of objects which can be stored in memory
-    # before commiting them to database during bulk auto add operation.
+    # before committing them to database during bulk auto add operation.
     chunk_size = 1000
 
     connector = models.CharField(
@@ -564,7 +564,7 @@ def _save_without_resurrecting(self):
 
     def _schedule_command(self):
         """
-        executes ``launch_command`` celery taks in the background
+        executes ``launch_command`` celery tasks in the background
         once changes are committed to the database
         """
         transaction.on_commit(lambda: launch_command.delay(self.pk))
diff --git a/openwisp_controller/connection/commands.py b/openwisp_controller/connection/commands.py
index 0e83011ec..9ad6c6a15 100644
--- a/openwisp_controller/connection/commands.py
+++ b/openwisp_controller/connection/commands.py
@@ -58,7 +58,7 @@
                             "title": _("Confirm Password"),
                         },
                     },
-                    "message": _("Your password must be atleast 6 characters long"),
+                    "message": _("Your password must be at least 6 characters long"),
                     "additionalProperties": False,
                     "definitions": {
                         "password_regex": {
diff --git a/openwisp_controller/connection/connectors/openwrt/ssh.py b/openwisp_controller/connection/connectors/openwrt/ssh.py
index f0907f783..fc19db6a9 100644
--- a/openwisp_controller/connection/connectors/openwrt/ssh.py
+++ b/openwisp_controller/connection/connectors/openwrt/ssh.py
@@ -11,7 +11,7 @@ class OpenWrt(Ssh):
     def update_config(self):
         try:
             output, exit_code = self.exec_command(
-                # "openwisp_config" for backword compatibility
+                # "openwisp_config" for backward compatibility
                 "(openwisp-config --version || openwisp_config --version) 2>/dev/null"
             )
         except Exception as error:
diff --git a/openwisp_controller/connection/connectors/ssh.py b/openwisp_controller/connection/connectors/ssh.py
index a6a1b87d9..52a585304 100644
--- a/openwisp_controller/connection/connectors/ssh.py
+++ b/openwisp_controller/connection/connectors/ssh.py
@@ -138,7 +138,7 @@ def _connect(self, address):
         """
         Tries to instantiate the SSH connection,
         if the connection fails, it tries again
-        by disabling the new deafult HostKeyAlgorithms
+        by disabling the new default HostKeyAlgorithms
         used by newer versions of Paramiko
         """
         params = self.params
@@ -187,11 +187,11 @@ def exec_command(
         # paramiko expects timeout as a float
         timeout = float(timeout)
         logger.info("Executing command: {0}".format(command))
-        # execute commmand
+        # execute command
         try:
             start_cmd = time.perf_counter()
             stdin, stdout, stderr = self.shell.exec_command(command, timeout=timeout)
-        # re-raise socket.timeout to avoid being catched
+        # re-raise socket.timeout to avoid being caught
         # by the subsequent `except Exception as e` block
         except socket.timeout:
             raise socket.timeout()
diff --git a/openwisp_controller/connection/tests/test_notifications.py b/openwisp_controller/connection/tests/test_notifications.py
index 3c45305ba..2c6db1b03 100644
--- a/openwisp_controller/connection/tests/test_notifications.py
+++ b/openwisp_controller/connection/tests/test_notifications.py
@@ -52,7 +52,7 @@ def test_default_notification_type_already_unregistered(self):
         # by some other module
 
         # Unregister "config_error" and "device_registered" notification
-        # types to avoid getting rasing ImproperlyConfigured exceptions
+        # types to avoid getting raising ImproperlyConfigured exceptions
         unregister_notification_type("connection_is_not_working")
         unregister_notification_type("connection_is_working")
 
diff --git a/openwisp_controller/connection/tests/test_selenium.py b/openwisp_controller/connection/tests/test_selenium.py
index db740dac3..e75af19d3 100644
--- a/openwisp_controller/connection/tests/test_selenium.py
+++ b/openwisp_controller/connection/tests/test_selenium.py
@@ -55,7 +55,7 @@ def test_command_widget_on_device(self):
         self.find_element(by=By.CSS_SELECTOR, value="#ow-command-confirm-yes").click()
 
         self.assertEqual(Command.objects.count(), 1)
-        # TODO: Selenium tests does not support websocket connections.
+        # TODO: Selenium tests do not support websocket connections.
         # Thus, we need to refresh the page. Remove this when support for
         # websockets is added.
         self.open(path)
diff --git a/openwisp_controller/connection/tests/utils.py b/openwisp_controller/connection/tests/utils.py
index ce122a25a..e8b477791 100644
--- a/openwisp_controller/connection/tests/utils.py
+++ b/openwisp_controller/connection/tests/utils.py
@@ -17,7 +17,7 @@ class SshServer(Server):
     def _run(self, *args, **kwargs):
         """
         Hides 'Bad file descriptor' system issue which
-        does not affect the effectivness of the tests
+        does not affect the effectiveness of the tests
         """
         try:
             return super()._run(*args, **kwargs)
diff --git a/openwisp_controller/geo/tests/pytest.py b/openwisp_controller/geo/tests/pytest.py
index e377520c4..fbe3a0e86 100644
--- a/openwisp_controller/geo/tests/pytest.py
+++ b/openwisp_controller/geo/tests/pytest.py
@@ -160,7 +160,7 @@ async def test_common_location_org_isolation(self):
         connected, _ = await admin_communicator.connect()
         assert connected
 
-        # Updating co-ordinates for org1_location should notify org1_user and admin,
+        # Updating coordinates for org1_location should notify org1_user and admin,
         await self._save_location(str(org1_location.pk))
         org1_response = await org1_communicator.receive_json_from(timeout=1)
         assert org1_response["id"] == str(org1_location.pk)
@@ -181,7 +181,7 @@ async def test_common_location_org_isolation(self):
         connected, _ = await org2_communicator.connect()
         assert connected
 
-        # Updating co-ordinates for org2_location should notify org2_user and admin,
+        # Updating coordinates for org2_location should notify org2_user and admin,
         await self._save_location(str(org2_location.pk))
         org2_response = await org2_communicator.receive_json_from(timeout=1)
         assert org2_response["id"] == str(org2_location.pk)
diff --git a/openwisp_controller/geo/tests/test_api.py b/openwisp_controller/geo/tests/test_api.py
index d50e7a833..156550692 100644
--- a/openwisp_controller/geo/tests/test_api.py
+++ b/openwisp_controller/geo/tests/test_api.py
@@ -185,14 +185,14 @@ def test_deactivated_device(self):
         url = "{0}?key={1}".format(reverse(self.url_name, args=[device.pk]), device.key)
         device.deactivate()
 
-        with self.subTest("Test retrieving device co-ordinates"):
+        with self.subTest("Test retrieving device coordinates"):
             response = self.client.get(
                 url,
                 content_type="application/json",
             )
             self.assertEqual(response.status_code, 200)
 
-        with self.subTest("Test updating device co-ordinates"):
+        with self.subTest("Test updating device coordinates"):
             response = self.client.put(
                 url,
                 content_type="application/json",
diff --git a/openwisp_controller/geo/tests/test_selenium.py b/openwisp_controller/geo/tests/test_selenium.py
index 1a24354c9..25995edae 100644
--- a/openwisp_controller/geo/tests/test_selenium.py
+++ b/openwisp_controller/geo/tests/test_selenium.py
@@ -4,7 +4,22 @@
 from django.test import tag
 from django.urls.base import reverse
 from django_loci.tests import TestAdminMixin
+from unittest.mock import MagicMock
+from django_loci.base import geocoding_views
 from django_loci.tests.base.test_selenium import BaseTestDeviceAdminSelenium
+from time import sleep
+from selenium.webdriver import ActionChains
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.support.ui import WebDriverWait
+
+class MockLocation:
+    def __init__(self, address="Lazio 00185, ITA", latitude=41.898903, longitude=12.512124):
+        self.address = address
+        self.latitude = latitude
+        self.longitude = longitude
+
+geocoding_views.geocode = MagicMock(return_value=MockLocation())
+geocoding_views.reverse_geocode = MagicMock(return_value=MockLocation())
 from selenium.webdriver.common.by import By
 from swapper import load_model
 
@@ -63,6 +78,39 @@ def _fill_device_form(self):
         self.find_element(by=By.CLASS_NAME, value="select2-results__option").click()
         super()._fill_device_form()
 
+    def test_real_time_update_address_field(self):
+        # Changing the address in tab 1 should update it in tab 0 in real time without a page reload.
+        # We increase the alert check timeout to 10s to prevent TimeoutException on slow CI runs.
+        location = self._create_location()
+        self.login()
+        url = reverse(f"admin:{self.app_label}_location_change", args=[location.id])
+        self.open(url)
+        self.web_driver.switch_to.new_window("tab")
+        tabs = self.web_driver.window_handles
+        self.web_driver.switch_to.window(tabs[-1])
+        self.open(url)
+        address_input = self.find_element(by=By.ID, value="id_address")
+        self.assertEqual(address_input.get_attribute("value"), location.address)
+        self.find_element(
+            by=By.XPATH, value='//a[@class="leaflet-draw-draw-marker"]'
+        ).click()
+        elem = self.find_element(by=By.ID, value="id_geometry-map")
+        ActionChains(self.web_driver).move_to_element(elem).move_by_offset(
+            30, 15
+        ).click().perform()
+        alert = WebDriverWait(self.web_driver, 10).until(EC.alert_is_present())
+        alert.accept()
+        sleep(0.05)
+        new_address = "Lazio 00185, ITA"
+        address_input = self.find_element(by=By.ID, value="id_address")
+        self.assertIn(new_address, address_input.get_attribute("value"))
+        self.wait_for("element_to_be_clickable", by=By.NAME, value="_continue").click()
+        self.web_driver.close()
+        initial_tab = tabs.index(tabs[-1]) - 1
+        self.web_driver.switch_to.window(tabs[initial_tab])
+        address_input = self.find_element(by=By.ID, value="id_address")
+        self.assertIn(new_address, address_input.get_attribute("value"))
+
 
 @tag("selenium_tests")
 class TestDeviceAdminReadonly(
@@ -108,10 +156,19 @@ def test_unsaved_changes_readonly(self):
             # so we just need to ensure it's set as expected
             self.web_driver.execute_script(
                 'django.jQuery(window).on("beforeunload", function(e) {'
+                " sessionStorage.setItem('unsaved_changes_alert', e.returnValue);"
                 " console.warn(e.returnValue); });"
             )
             self.web_driver.refresh()
-            for entry in self.get_browser_logs():
+            alert = self.web_driver.execute_script(
+                "var alert = sessionStorage.getItem('unsaved_changes_alert');"
+                "sessionStorage.removeItem('unsaved_changes_alert');"
+                "return alert;"
+            )
+            if alert and "You haven't saved your changes yet!" in alert:
+                self.fail("Unsaved changes alert displayed without any change")
+
+            for entry in self.get_browser_logs() or []:
                 if (
                     entry["level"] == "WARNING"
                     and "You haven't saved your changes yet!" in entry["message"]
diff --git a/openwisp_controller/pki/base/models.py b/openwisp_controller/pki/base/models.py
index f93767329..803d8f84a 100644
--- a/openwisp_controller/pki/base/models.py
+++ b/openwisp_controller/pki/base/models.py
@@ -9,7 +9,24 @@
 from ..utils import UnqiueCommonNameMixin
 
 
+# Avoids "DateTimeField received a naive datetime while time zone support is active"
+# warning by returning an aware datetime when USE_TZ is True.
+def default_validity_start():
+    from datetime import datetime, timedelta
+    from django.conf import settings
+    from django.utils import timezone
+    start = datetime.now() - timedelta(days=1)
+    start = start.replace(hour=0, minute=0, second=0, microsecond=0)
+    if settings.USE_TZ:
+        return timezone.make_aware(start)
+    return start
+
+
 class AbstractCa(ShareableOrgMixin, UnqiueCommonNameMixin, BaseCa):
+    validity_start = models.DateTimeField(
+        blank=True, null=True, default=default_validity_start
+    )
+
     class Meta(BaseCa.Meta):
         abstract = True
         constraints = [
@@ -21,6 +38,9 @@ class Meta(BaseCa.Meta):
 
 
 class AbstractCert(ShareableOrgMixin, UnqiueCommonNameMixin, BaseCert):
+    validity_start = models.DateTimeField(
+        blank=True, null=True, default=default_validity_start
+    )
     ca = models.ForeignKey(
         get_model_name("django_x509", "Ca"),
         verbose_name=_("CA"),
diff --git a/openwisp_controller/pki/migrations/0013_alter_ca_validity_start_alter_cert_validity_start.py b/openwisp_controller/pki/migrations/0013_alter_ca_validity_start_alter_cert_validity_start.py
new file mode 100644
index 000000000..1ec87dab7
--- /dev/null
+++ b/openwisp_controller/pki/migrations/0013_alter_ca_validity_start_alter_cert_validity_start.py
@@ -0,0 +1,30 @@
+import openwisp_controller.pki.base.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("pki", "0012_alter_ca_extensions_alter_ca_key_length_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="ca",
+            name="validity_start",
+            field=models.DateTimeField(
+                blank=True,
+                default=openwisp_controller.pki.base.models.default_validity_start,
+                null=True,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="cert",
+            name="validity_start",
+            field=models.DateTimeField(
+                blank=True,
+                default=openwisp_controller.pki.base.models.default_validity_start,
+                null=True,
+            ),
+        ),
+    ]
diff --git a/openwisp_controller/subnet_division/base/models.py b/openwisp_controller/subnet_division/base/models.py
index b6dd58c57..4ee77d240 100644
--- a/openwisp_controller/subnet_division/base/models.py
+++ b/openwisp_controller/subnet_division/base/models.py
@@ -132,7 +132,7 @@ def _validate_master_subnet_consistency(self):
             raise ValidationError(
                 {
                     "number_of_subnets": _(
-                        "The master subnet is too small to acommodate the "
+                        "The master subnet is too small to accommodate the "
                         'requested "number of subnets" plus the reserved '
                         "subnet, please increase the size of the master "
                         'subnet or decrease the "size of subnets" field.'
diff --git a/openwisp_controller/subnet_division/rule_types/base.py b/openwisp_controller/subnet_division/rule_types/base.py
index 2b51797b8..e22c565ca 100644
--- a/openwisp_controller/subnet_division/rule_types/base.py
+++ b/openwisp_controller/subnet_division/rule_types/base.py
@@ -177,7 +177,7 @@ def get_config(cls, instance):
         # check for real existence in DB to workaround
         # this django-import-export bug:
         # https://github.com/django-import-export/django-import-export/issues/1078
-        # TODO: if that issue is ever solved, we can remove the this block below
+        # TODO: if that issue is ever solved, we can remove this block below
         Config = config._meta.model
         if not Config.objects.filter(pk=config.pk).exists():
             raise ObjectDoesNotExist()
diff --git a/openwisp_controller/subnet_division/tests/test_models.py b/openwisp_controller/subnet_division/tests/test_models.py
index 7137d596c..2377399c8 100644
--- a/openwisp_controller/subnet_division/tests/test_models.py
+++ b/openwisp_controller/subnet_division/tests/test_models.py
@@ -178,7 +178,7 @@ def test_field_validations(self):
                 rule.full_clean()
             expected_message_dict = {
                 "number_of_subnets": [
-                    "The master subnet is too small to acommodate "
+                    "The master subnet is too small to accommodate "
                     'the requested "number of subnets" plus the '
                     "reserved subnet, please increase the size of "
                     "the master subnet or decrease the "
@@ -279,7 +279,7 @@ def test_slash_32_rule_ipv4_error(self):
         except ValidationError as e:
             self.assertIn("number_of_subnets", e.message_dict)
             self.assertIn(
-                "The master subnet is too small to acommodate",
+                "The master subnet is too small to accommodate",
                 e.message_dict["number_of_subnets"][0],
             )
         else:
@@ -315,7 +315,7 @@ def test_slash_128_rule_ipv6_error(self):
         except ValidationError as e:
             self.assertIn("number_of_subnets", e.message_dict)
             self.assertIn(
-                "The master subnet is too small to acommodate",
+                "The master subnet is too small to accommodate",
                 e.message_dict["number_of_subnets"][0],
             )
         else:
@@ -495,7 +495,7 @@ def test_subnets_exhausted(self, mocked_logger, *args):
         subnet = self._get_master_subnet(
             "10.0.0.0/29", master_subnet=self.master_subnet
         )
-        # The master subnet can acommodate
+        # The master subnet can accommodate
         # this rule only once:
         # A /29 has 4 /31 slots available
         # Minus the reserved subnet = 3
diff --git a/openwisp_controller/tests/test_selenium.py b/openwisp_controller/tests/test_selenium.py
index 8a3c94f45..208bed20c 100644
--- a/openwisp_controller/tests/test_selenium.py
+++ b/openwisp_controller/tests/test_selenium.py
@@ -89,7 +89,7 @@ def test_restoring_deleted_device(self, *args):
         # is logged at WARNING level.
         # By checking that there are no WARNING level errors logged in the
         # browser console, we ensure that this issue is not happening.
-        for error in self.get_browser_logs():
+        for error in self.get_browser_logs() or []:
             if error["level"] == "WARNING" and error["message"] not in [
                 "wrong event specified: touchleave"
             ]:
diff --git a/tests/openwisp2/sample_pki/migrations/0005_alter_ca_validity_start_alter_cert_validity_start.py b/tests/openwisp2/sample_pki/migrations/0005_alter_ca_validity_start_alter_cert_validity_start.py
new file mode 100644
index 000000000..53e86db31
--- /dev/null
+++ b/tests/openwisp2/sample_pki/migrations/0005_alter_ca_validity_start_alter_cert_validity_start.py
@@ -0,0 +1,32 @@
+# Generated by Django 5.2.15 on 2026-06-16 16:34
+
+import openwisp_controller.pki.base.models
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("sample_pki", "0004_alter_ca_extensions_alter_ca_key_length_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="ca",
+            name="validity_start",
+            field=models.DateTimeField(
+                blank=True,
+                default=openwisp_controller.pki.base.models.default_validity_start,
+                null=True,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="cert",
+            name="validity_start",
+            field=models.DateTimeField(
+                blank=True,
+                default=openwisp_controller.pki.base.models.default_validity_start,
+                null=True,
+            ),
+        ),
+    ]