diff --git a/openwisp_controller/connection/base/models.py b/openwisp_controller/connection/base/models.py
index 66452fc4a..70c1e57ed 100644
--- a/openwisp_controller/connection/base/models.py
+++ b/openwisp_controller/connection/base/models.py
@@ -545,7 +545,8 @@ def _exec_command(self):
             command = self.get_type_display()
         # user registered command
         else:
-            command = self._callable(**self.input)
+            input = self.input or {}
+            command = self._callable(**input)
             output, exit_code = self.connection.connector_instance.exec_command(
                 command, raise_unexpected_exit=False
             )
diff --git a/openwisp_controller/connection/commands.py b/openwisp_controller/connection/commands.py
index 50dbe70ad..725e82847 100644
--- a/openwisp_controller/connection/commands.py
+++ b/openwisp_controller/connection/commands.py
@@ -25,12 +25,20 @@
                     },
                     'message': _('Command cannot be empty.'),
                     'required': ['command'],
+                    'additionalProperties': False,
                 },
             },
         ),
         (
             'reboot',
-            {'label': _('Reboot'), 'schema': {'title': _('Reboot'), 'type': 'null'}},
+            {
+                'label': _('Reboot'),
+                'schema': {
+                    'title': _('Reboot'),
+                    'type': 'null',
+                    'additionalProperties': False,
+                },
+            },
         ),
         (
             'change_password',
diff --git a/openwisp_controller/connection/static/connection/js/commands.js b/openwisp_controller/connection/static/connection/js/commands.js
index ba91f485f..ce0848526 100644
--- a/openwisp_controller/connection/static/connection/js/commands.js
+++ b/openwisp_controller/connection/static/connection/js/commands.js
@@ -397,8 +397,9 @@ function initCommandOverlay($) {
     });
 
     function closeOverlay() {
-        $('#id_command_set-0-type').val('reboot');
-        $('#id_command_set-0-type').trigger('change');
+        // The user may close the form without submitting it.
+        // The following line ensures that all input fields are cleared.
+        $('#command_set-0 .jsoneditor-wrapper input').val('');
         $('#command_set-group').css('display', 'none');
         $('.ow-command-overlay-errornote').addClass('ow-hide');
         commandConfirmationDialog.hide();
diff --git a/openwisp_controller/connection/tests/test_command_utilities.py b/openwisp_controller/connection/tests/test_command_utilities.py
index a5e947412..cc5060462 100644
--- a/openwisp_controller/connection/tests/test_command_utilities.py
+++ b/openwisp_controller/connection/tests/test_command_utilities.py
@@ -5,7 +5,7 @@
 
 
 class TestCommandUtilities(TestCase):
-    REBOOT_SCHEMA = {'title': 'Reboot', 'type': 'null'}
+    REBOOT_SCHEMA = {'title': 'Reboot', 'type': 'null', 'additionalProperties': False}
 
     def test_get_command_schema(self):
         with self.subTest('Test existing command option'):
diff --git a/openwisp_controller/connection/tests/test_models.py b/openwisp_controller/connection/tests/test_models.py
index ca1d10bfa..b89e54290 100644
--- a/openwisp_controller/connection/tests/test_models.py
+++ b/openwisp_controller/connection/tests/test_models.py
@@ -786,6 +786,47 @@ def _command_assertions(destination_address, mocked_exec_command):
         unregister_command('callable_ping')
         unregister_command('path_ping')
 
+    @mock.patch(_connect_path)
+    @mock.patch.dict(COMMANDS, {})
+    @mock.patch.dict(ORGANIZATION_ENABLED_COMMANDS, {'__all__': ('restart_network')})
+    @mock.patch(_exec_command_path)
+    def test_execute_user_registered_command_without_input(
+        self, mocked_exec_command, connect_mocked
+    ):
+        restart_network_schema = {
+            'label': 'Restart Network',
+            'schema': {
+                'title': 'Restart Network',
+                'type': 'null',
+                'additionalProperties': False,
+            },
+            'callable': 'openwisp_controller.connection.tests.utils'
+            '._restart_network_command_callable',
+        }
+        dc = self._create_device_connection()
+        register_command('restart_network', restart_network_schema)
+        command = Command(
+            device=dc.device,
+            connection=dc,
+            type='restart_network',
+        )
+        command.full_clean()
+        mocked_exec_command.return_value = self._exec_command_return_value(
+            stdout='Network restarted'
+        )
+        command.save()
+        # must call this explicitly because lack of transactions in this test case
+        command.execute()
+        connect_mocked.assert_called()
+        mocked_exec_command.assert_called_once()
+        mocked_exec_command.assert_called_with(
+            '/etc/init.d/networking restart',
+            timeout=app_settings.SSH_COMMAND_TIMEOUT,
+        )
+        command.refresh_from_db()
+        self.assertEqual(command.status, 'success')
+        self.assertEqual(command.output, 'Network restarted\n')
+
     def test_command_permissions(self):
         ct = ContentType.objects.get_by_natural_key(
             app_label=self.app_label, model='command'
diff --git a/openwisp_controller/connection/tests/utils.py b/openwisp_controller/connection/tests/utils.py
index f2328308f..740c8d4e4 100644
--- a/openwisp_controller/connection/tests/utils.py
+++ b/openwisp_controller/connection/tests/utils.py
@@ -138,3 +138,7 @@ def _ping_command_callable(destination_address, interface_name=None):
     if interface_name:
         command += f' -I {interface_name}'
     return command
+
+
+def _restart_network_command_callable():
+    return '/etc/init.d/networking restart'