diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index 3361679591..db1e877a74 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -1319,7 +1319,7 @@ class ModelAdmin(BaseModelAdmin):
         if IS_POPUP_VAR in request.POST:
             popup_response_data = json.dumps({
                 'action': 'delete',
-                'value': obj_id,
+                'value': str(obj_id),
             })
             return SimpleTemplateResponse('admin/popup_response.html', {
                 'popup_response_data': popup_response_data,
diff --git a/tests/admin_views/models.py b/tests/admin_views/models.py
index 5411885ee9..2c7a217c42 100644
--- a/tests/admin_views/models.py
+++ b/tests/admin_views/models.py
@@ -968,4 +968,4 @@ class ParentWithUUIDPK(models.Model):
 
 
 class RelatedWithUUIDPKModel(models.Model):
-    parent = models.ForeignKey(ParentWithUUIDPK, on_delete=models.CASCADE)
+    parent = models.ForeignKey(ParentWithUUIDPK, on_delete=models.SET_NULL, null=True, blank=True)
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index 0f46496c73..983689fd5c 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -4546,6 +4546,23 @@ class SeleniumAdminViewsFirefoxTests(AdminSeleniumWebDriverTestCase):
         self.assertEqual(select.first_selected_option.text, uuid_id)
         self.assertEqual(select.first_selected_option.get_attribute('value'), uuid_id)
 
+    def test_inline_uuid_pk_delete_with_popup(self):
+        from selenium.webdriver.support.ui import Select
+        parent = ParentWithUUIDPK.objects.create(title='test')
+        related_with_parent = RelatedWithUUIDPKModel.objects.create(parent=parent)
+        self.admin_login(username='super', password='secret', login_url=reverse('admin:index'))
+        change_url = reverse('admin:admin_views_relatedwithuuidpkmodel_change', args=(related_with_parent.id,))
+        self.selenium.get(self.live_server_url + change_url)
+        self.selenium.find_element_by_id('delete_id_parent').click()
+        self.wait_for_popup()
+        self.selenium.switch_to.window(self.selenium.window_handles[-1])
+        self.selenium.find_element_by_xpath('//input[@value="Yes, I\'m sure"]').click()
+        self.selenium.switch_to.window(self.selenium.window_handles[0])
+        select = Select(self.selenium.find_element_by_id('id_parent'))
+        self.assertEqual(ParentWithUUIDPK.objects.count(), 0)
+        self.assertEqual(select.first_selected_option.text, '---------')
+        self.assertEqual(select.first_selected_option.get_attribute('value'), '')
+
 
 class SeleniumAdminViewsChromeTests(SeleniumAdminViewsFirefoxTests):
     webdriver_class = 'selenium.webdriver.chrome.webdriver.WebDriver'