diff --git a/django/test/testcases.py b/django/test/testcases.py
index b0fd5e89a1..871f141725 100644
--- a/django/test/testcases.py
+++ b/django/test/testcases.py
@@ -54,7 +54,7 @@ from django.test.utils import (
     modify_settings,
     override_settings,
 )
-from django.utils.deprecation import RemovedInDjango50Warning
+from django.utils.deprecation import RemovedInDjango50Warning, RemovedInDjango51Warning
 from django.utils.functional import classproperty
 from django.utils.version import PY310
 from django.views.static import serve
@@ -206,18 +206,18 @@ class _AssertFormErrorDeprecationHelper:
             )
 
     @staticmethod
-    def assertFormsetError(
+    def assertFormSetError(
         self, response, formset, form_index, field, errors, msg_prefix=""
     ):
         """
         Search for a formset named "formset" in the "response" and dispatch to
-        the new assertFormsetError() using that instance. If the name is found
+        the new assertFormSetError() using that instance. If the name is found
         in multiple contexts they're all checked in order and any failure will
         abort the test.
         """
         warning_msg = (
-            f"Passing response to assertFormsetError() is deprecated. Use the formset "
-            f"object directly: assertFormsetError(response.context[{formset!r}], "
+            f"Passing response to assertFormSetError() is deprecated. Use the formset "
+            f"object directly: assertFormSetError(response.context[{formset!r}], "
             f"{form_index!r}, ...)"
         )
         warnings.warn(warning_msg, RemovedInDjango50Warning, stacklevel=2)
@@ -234,7 +234,7 @@ class _AssertFormErrorDeprecationHelper:
             if formset not in context or not hasattr(context[formset], "forms"):
                 continue
             found_formset = True
-            self.assertFormsetError(
+            self.assertFormSetError(
                 context[formset], form_index, field, errors, msg_prefix
             )
         if not found_formset:
@@ -737,10 +737,19 @@ class SimpleTestCase(unittest.TestCase):
         errors = to_list(errors)
         self._assert_form_error(form, field, errors, msg_prefix, f"form {form!r}")
 
+    # RemovedInDjango51Warning.
+    def assertFormsetError(self, *args, **kw):
+        warnings.warn(
+            "assertFormsetError() is deprecated in favor of assertFormSetError().",
+            category=RemovedInDjango51Warning,
+            stacklevel=2,
+        )
+        return self.assertFormSetError(*args, **kw)
+
     # RemovedInDjango50Warning: When the deprecation ends, remove the
     # decorator.
     @_AssertFormErrorDeprecationHelper.patch_signature
-    def assertFormsetError(self, formset, form_index, field, errors, msg_prefix=""):
+    def assertFormSetError(self, formset, form_index, field, errors, msg_prefix=""):
         """
         Similar to assertFormError() but for formsets.
 
@@ -752,7 +761,7 @@ class SimpleTestCase(unittest.TestCase):
         """
         if errors is None:
             warnings.warn(
-                "Passing errors=None to assertFormsetError() is deprecated, "
+                "Passing errors=None to assertFormSetError() is deprecated, "
                 "use errors=[] instead.",
                 RemovedInDjango50Warning,
                 stacklevel=2,
diff --git a/docs/internals/deprecation.txt b/docs/internals/deprecation.txt
index a5b76c13ab..cbde99fb06 100644
--- a/docs/internals/deprecation.txt
+++ b/docs/internals/deprecation.txt
@@ -35,6 +35,8 @@ details on these changes.
 * The ``map_width`` and ``map_height`` attributes of ``BaseGeometryWidget``
   will be removed.
 
+* The ``SimpleTestCase.assertFormsetError()`` method will be removed.
+
 .. _deprecation-removed-in-5.0:
 
 5.0
diff --git a/docs/releases/1.6.txt b/docs/releases/1.6.txt
index 4109565448..2d77c7dc85 100644
--- a/docs/releases/1.6.txt
+++ b/docs/releases/1.6.txt
@@ -321,7 +321,7 @@ Minor features
 
 * The :class:`~django.test.SimpleTestCase` class includes a new assertion
   helper for testing formset errors:
-  :meth:`~django.test.SimpleTestCase.assertFormsetError`.
+  ``django.test.SimpleTestCase.assertFormsetError()``.
 
 * The list of related fields added to a
   :class:`~django.db.models.query.QuerySet` by
diff --git a/docs/releases/4.0.1.txt b/docs/releases/4.0.1.txt
index d5e129a153..dba3f1783f 100644
--- a/docs/releases/4.0.1.txt
+++ b/docs/releases/4.0.1.txt
@@ -50,8 +50,7 @@ Bugfixes
 ========
 
 * Fixed a regression in Django 4.0 that caused a crash of
-  :meth:`~django.test.SimpleTestCase.assertFormsetError` on a formset named
-  ``form`` (:ticket:`33346`).
+  ``assertFormsetError()`` on a formset named ``form`` (:ticket:`33346`).
 
 * Fixed a bug in Django 4.0 that caused a crash on booleans with the
   ``RedisCache`` backend (:ticket:`33361`).
diff --git a/docs/releases/4.1.txt b/docs/releases/4.1.txt
index 08fb7c2abc..55e19e09ea 100644
--- a/docs/releases/4.1.txt
+++ b/docs/releases/4.1.txt
@@ -407,8 +407,8 @@ Tests
   raises a ``RuntimeError``, the same as outside of tests.
 
 * :meth:`.SimpleTestCase.assertFormError` and
-  :meth:`~.SimpleTestCase.assertFormsetError` now support passing a
-  form/formset object directly.
+  :meth:`assertFormsetError() <django.test.SimpleTestCase.assertFormSetError>`
+  now support passing a form/formset object directly.
 
 URLs
 ~~~~
@@ -671,8 +671,8 @@ Miscellaneous
 
 * The undocumented ability to pass ``errors=None`` to
   :meth:`.SimpleTestCase.assertFormError` and
-  :meth:`~.SimpleTestCase.assertFormsetError` is deprecated. Use ``errors=[]``
-  instead.
+  :meth:`assertFormsetError() <django.test.SimpleTestCase.assertFormSetError>`
+  is deprecated. Use ``errors=[]`` instead.
 
 * ``django.contrib.sessions.serializers.PickleSerializer`` is deprecated due to
   the risk of remote code execution.
diff --git a/docs/releases/4.2.txt b/docs/releases/4.2.txt
index 5774bfef7b..33035d7881 100644
--- a/docs/releases/4.2.txt
+++ b/docs/releases/4.2.txt
@@ -419,3 +419,6 @@ Miscellaneous
 
 * The ``map_height`` and ``map_width`` attributes of ``BaseGeometryWidget`` are
   deprecated, use CSS to size map widgets instead.
+
+* ``SimpleTestCase.assertFormsetError()`` is deprecated in favor of
+  ``assertFormSetError()``.
diff --git a/docs/topics/testing/tools.txt b/docs/topics/testing/tools.txt
index 1f235d920b..4e2003acde 100644
--- a/docs/topics/testing/tools.txt
+++ b/docs/topics/testing/tools.txt
@@ -1573,16 +1573,16 @@ your test suite.
         ``assertFormError()`` is deprecated and will be removed in Django 5.0.
         Use the form instance directly instead.
 
-.. method:: SimpleTestCase.assertFormsetError(formset, form_index, field, errors, msg_prefix='')
+.. method:: SimpleTestCase.assertFormSetError(formset, form_index, field, errors, msg_prefix='')
 
     Asserts that the ``formset`` raises the provided list of errors when
     rendered.
 
-    ``formset`` is a ``Formset`` instance. The formset must be bound but not
-    necessarily validated (``assertFormsetError()`` will automatically call the
+    ``formset`` is a ``FormSet`` instance. The formset must be bound but not
+    necessarily validated (``assertFormSetError()`` will automatically call the
     ``full_clean()`` on the formset).
 
-    ``form_index`` is the number of the form within the ``Formset`` (starting
+    ``form_index`` is the number of the form within the ``FormSet`` (starting
     from 0). Use ``form_index=None`` to check the formset's non-form errors,
     i.e. the errors you get when calling ``formset.non_form_errors()``. In that
     case you must also use ``field=None``.
@@ -1593,9 +1593,14 @@ your test suite.
     .. deprecated:: 4.1
 
         Support for passing a response object and a formset name to
-        ``assertFormsetError()`` is deprecated and will be removed in Django
+        ``assertFormSetError()`` is deprecated and will be removed in Django
         5.0. Use the formset instance directly instead.
 
+    .. deprecated:: 4.2
+
+        The ``assertFormsetError()`` assertion method is deprecated. Use
+        ``assertFormSetError()`` instead.
+
 .. method:: SimpleTestCase.assertContains(response, text, count=None, status_code=200, msg_prefix='', html=False)
 
     Asserts that a :class:`response <django.http.HttpResponse>` produced the
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index cd5b8ed836..9796703ad1 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -8110,7 +8110,7 @@ class AdminViewOnSiteTests(TestCase):
         Issue #20522
         Verifying that if the parent form fails validation, the inlines also
         run validation even if validation is contingent on parent form data.
-        Also, assertFormError() and assertFormsetError() is usable for admin
+        Also, assertFormError() and assertFormSetError() is usable for admin
         forms and formsets.
         """
         # The form validation should fail because 'some_required_info' is
@@ -8134,7 +8134,7 @@ class AdminViewOnSiteTests(TestCase):
             ["This field is required."],
         )
         self.assertFormError(response.context["adminform"], None, [])
-        self.assertFormsetError(
+        self.assertFormSetError(
             response.context["inline_admin_formset"],
             0,
             None,
@@ -8143,7 +8143,7 @@ class AdminViewOnSiteTests(TestCase):
                 "contrived test case"
             ],
         )
-        self.assertFormsetError(
+        self.assertFormSetError(
             response.context["inline_admin_formset"], None, None, []
         )
 
@@ -8179,7 +8179,7 @@ class AdminViewOnSiteTests(TestCase):
             "some_required_info",
             ["This field is required."],
         )
-        self.assertFormsetError(
+        self.assertFormSetError(
             response.context["inline_admin_formset"],
             0,
             None,
diff --git a/tests/test_utils/tests.py b/tests/test_utils/tests.py
index 709060d76f..b22aa273d5 100644
--- a/tests/test_utils/tests.py
+++ b/tests/test_utils/tests.py
@@ -46,7 +46,7 @@ from django.test.utils import (
     setup_test_environment,
 )
 from django.urls import NoReverseMatch, path, reverse, reverse_lazy
-from django.utils.deprecation import RemovedInDjango50Warning
+from django.utils.deprecation import RemovedInDjango50Warning, RemovedInDjango51Warning
 from django.utils.log import DEFAULT_LOGGING
 from django.utils.version import PY311
 
@@ -1517,44 +1517,53 @@ class AssertFormErrorTests(SimpleTestCase):
             )
 
 
-class AssertFormsetErrorTests(SimpleTestCase):
+class AssertFormSetErrorTests(SimpleTestCase):
     @ignore_warnings(category=RemovedInDjango50Warning)
     def test_non_client_response(self):
         msg = (
-            "assertFormsetError() is only usable on responses fetched using "
+            "assertFormSetError() is only usable on responses fetched using "
             "the Django test Client."
         )
         response = HttpResponse()
         with self.assertRaisesMessage(ValueError, msg):
-            self.assertFormsetError(response, "formset", 0, "field", "invalid value")
+            self.assertFormSetError(response, "formset", 0, "field", "invalid value")
 
     @ignore_warnings(category=RemovedInDjango50Warning)
     def test_response_with_no_context(self):
         msg = "Response did not use any contexts to render the response"
         response = mock.Mock(context=[])
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(response, "formset", 0, "field", "invalid value")
+            self.assertFormSetError(response, "formset", 0, "field", "invalid value")
 
     @ignore_warnings(category=RemovedInDjango50Warning)
     def test_formset_not_in_context(self):
         msg = "The formset 'formset' was not used to render the response"
         response = mock.Mock(context=[{}])
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(response, "formset", 0, "field", "invalid value")
+            self.assertFormSetError(response, "formset", 0, "field", "invalid value")
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 response, "formset", 0, "field", "invalid value", msg_prefix=msg_prefix
             )
 
-    def test_single_error(self):
+    def test_rename_assertformseterror_deprecation_warning(self):
+        msg = "assertFormsetError() is deprecated in favor of assertFormSetError()."
+        with self.assertRaisesMessage(RemovedInDjango51Warning, msg):
+            self.assertFormsetError()
+
+    @ignore_warnings(category=RemovedInDjango51Warning)
+    def test_deprecated_assertformseterror(self):
         self.assertFormsetError(TestFormset.invalid(), 0, "field", "invalid value")
 
+    def test_single_error(self):
+        self.assertFormSetError(TestFormset.invalid(), 0, "field", "invalid value")
+
     def test_error_list(self):
-        self.assertFormsetError(TestFormset.invalid(), 0, "field", ["invalid value"])
+        self.assertFormSetError(TestFormset.invalid(), 0, "field", ["invalid value"])
 
     def test_empty_errors_valid_formset(self):
-        self.assertFormsetError(TestFormset.valid(), 0, "field", [])
+        self.assertFormSetError(TestFormset.valid(), 0, "field", [])
 
     def test_multiple_forms(self):
         formset = TestFormset(
@@ -1566,8 +1575,8 @@ class AssertFormsetErrorTests(SimpleTestCase):
             }
         )
         formset.full_clean()
-        self.assertFormsetError(formset, 0, "field", [])
-        self.assertFormsetError(formset, 1, "field", ["invalid value"])
+        self.assertFormSetError(formset, 0, "field", [])
+        self.assertFormSetError(formset, 1, "field", ["invalid value"])
 
     def test_field_not_in_form(self):
         msg = (
@@ -1575,12 +1584,12 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "does not contain the field 'other_field'."
         )
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(), 0, "other_field", "invalid value"
             )
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(),
                 0,
                 "other_field",
@@ -1594,11 +1603,11 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "valid=True total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(TestFormset.valid(), 0, "field", "invalid value")
+            self.assertFormSetError(TestFormset.valid(), 0, "field", "invalid value")
         self.assertIn("[] != ['invalid value']", str(ctx.exception))
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.valid(), 0, "field", "invalid value", msg_prefix=msg_prefix
             )
 
@@ -1608,11 +1617,11 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "valid=False total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(TestFormset.invalid(), 0, "field", "other error")
+            self.assertFormSetError(TestFormset.invalid(), 0, "field", "other error")
         self.assertIn("['invalid value'] != ['other error']", str(ctx.exception))
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(), 0, "field", "other error", msg_prefix=msg_prefix
             )
 
@@ -1622,7 +1631,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "bound, it will never have any errors."
         )
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(TestFormset(), 0, "field", [])
+            self.assertFormSetError(TestFormset(), 0, "field", [])
 
     def test_empty_errors_invalid_formset(self):
         msg = (
@@ -1630,11 +1639,11 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "valid=False total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(TestFormset.invalid(), 0, "field", [])
+            self.assertFormSetError(TestFormset.invalid(), 0, "field", [])
         self.assertIn("['invalid value'] != []", str(ctx.exception))
 
     def test_non_field_errors(self):
-        self.assertFormsetError(
+        self.assertFormSetError(
             TestFormset.invalid(nonfield=True), 0, None, "non-field error"
         )
 
@@ -1644,7 +1653,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "valid=False total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(nonfield=True), 0, None, "other non-field error"
             )
         self.assertIn(
@@ -1652,7 +1661,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
         )
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(nonfield=True),
                 0,
                 None,
@@ -1666,16 +1675,16 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "valid=False total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(TestFormset.invalid(), 0, None, "non-field error")
+            self.assertFormSetError(TestFormset.invalid(), 0, None, "non-field error")
         self.assertIn("[] != ['non-field error']", str(ctx.exception))
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(), 0, None, "non-field error", msg_prefix=msg_prefix
             )
 
     def test_non_form_errors(self):
-        self.assertFormsetError(TestFormset.invalid(nonform=True), None, None, "error")
+        self.assertFormSetError(TestFormset.invalid(nonform=True), None, None, "error")
 
     def test_different_non_form_errors(self):
         msg = (
@@ -1683,13 +1692,13 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "total_forms=0> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(nonform=True), None, None, "other error"
             )
         self.assertIn("['error'] != ['other error']", str(ctx.exception))
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(nonform=True),
                 None,
                 None,
@@ -1703,11 +1712,11 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg) as ctx:
-            self.assertFormsetError(TestFormset.invalid(), None, None, "error")
+            self.assertFormSetError(TestFormset.invalid(), None, None, "error")
         self.assertIn("[] != ['error']", str(ctx.exception))
         msg_prefix = "Custom prefix"
         with self.assertRaisesMessage(AssertionError, f"{msg_prefix}: {msg}"):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(),
                 None,
                 None,
@@ -1718,7 +1727,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
     def test_non_form_errors_with_field(self):
         msg = "You must use field=None with form_index=None."
         with self.assertRaisesMessage(ValueError, msg):
-            self.assertFormsetError(
+            self.assertFormSetError(
                 TestFormset.invalid(nonform=True), None, "field", "error"
             )
 
@@ -1728,7 +1737,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "1 form."
         )
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(TestFormset.invalid(), 2, "field", "error")
+            self.assertFormSetError(TestFormset.invalid(), 2, "field", "error")
 
     def test_form_index_too_big_plural(self):
         formset = TestFormset(
@@ -1745,7 +1754,7 @@ class AssertFormsetErrorTests(SimpleTestCase):
             "forms."
         )
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(formset, 2, "field", "error")
+            self.assertFormSetError(formset, 2, "field", "error")
 
 
 # RemovedInDjango50Warning
@@ -1845,15 +1854,15 @@ class AssertFormErrorDeprecationTests(SimpleTestCase):
             "valid=False total_forms=1> don't match."
         )
         with self.assertRaisesMessage(AssertionError, msg):
-            self.assertFormsetError(TestFormset.invalid(), 0, "field", None)
+            self.assertFormSetError(TestFormset.invalid(), 0, "field", None)
 
     def test_assert_formset_error_errors_none_warning(self):
         msg = (
-            "Passing errors=None to assertFormsetError() is deprecated, use "
+            "Passing errors=None to assertFormSetError() is deprecated, use "
             "errors=[] instead."
         )
         with self.assertWarnsMessage(RemovedInDjango50Warning, msg):
-            self.assertFormsetError(TestFormset.valid(), 0, "field", None)
+            self.assertFormSetError(TestFormset.valid(), 0, "field", None)
 
     def _assert_formset_error_old_api_cases(
         self, formset, form_index, field, errors, msg_prefix
@@ -1933,8 +1942,8 @@ class AssertFormErrorDeprecationTests(SimpleTestCase):
 
     def test_assert_formset_error_old_api(self):
         deprecation_msg = (
-            "Passing response to assertFormsetError() is deprecated. Use the formset "
-            "object directly: assertFormsetError(response.context['formset'], 0, ...)"
+            "Passing response to assertFormSetError() is deprecated. Use the formset "
+            "object directly: assertFormSetError(response.context['formset'], 0, ...)"
         )
         for args, kwargs in self._assert_formset_error_old_api_cases(
             formset="formset",
@@ -1945,7 +1954,7 @@ class AssertFormErrorDeprecationTests(SimpleTestCase):
         ):
             with self.subTest(args=args, kwargs=kwargs):
                 with self.assertWarnsMessage(RemovedInDjango50Warning, deprecation_msg):
-                    self.assertFormsetError(*args, **kwargs)
+                    self.assertFormSetError(*args, **kwargs)
 
     @ignore_warnings(category=RemovedInDjango50Warning)
     def test_assert_formset_error_old_api_assertion_error(self):
@@ -1958,7 +1967,7 @@ class AssertFormErrorDeprecationTests(SimpleTestCase):
         ):
             with self.subTest(args=args, kwargs=kwargs):
                 with self.assertRaises(AssertionError):
-                    self.assertFormsetError(*args, **kwargs)
+                    self.assertFormSetError(*args, **kwargs)
 
 
 class FirstUrls: