diff --git a/docs/source/conf.py b/docs/source/conf.py
index 72d9d43da..760f0dde1 100755
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -26,9 +26,12 @@
     "sphinxcontrib.spelling",
     "sphinxcontrib.autohttp.flask",
     "sphinx_toolbox.more_autodoc.autoprotocol",
-    "enum_tools.autoenum",
 ]
 
+# Required by sphinx-toolbox 4.2.0rc1 for compatibility with Sphinx 9.
+# See https://github.com/sphinx-toolbox/sphinx-toolbox/issues/201#issuecomment-4313483053.
+autodoc_use_legacy_class_based = True
+
 templates_path = ["_templates"]
 source_suffix = ".rst"
 master_doc = "index"
diff --git a/docs/source/mock-api-reference.rst b/docs/source/mock-api-reference.rst
index 1b2ea255a..19a6185c4 100644
--- a/docs/source/mock-api-reference.rst
+++ b/docs/source/mock-api-reference.rst
@@ -25,11 +25,11 @@ API Reference
    :undoc-members:
    :exclude-members: to_dict, from_dict, not_deleted_targets
 
-.. autoenum:: mock_vws.states.States
+.. autoclass:: mock_vws.states.States
    :members:
    :undoc-members:
 
-.. autoenum:: mock_vws.database_type.DatabaseType
+.. autoclass:: mock_vws.database_type.DatabaseType
    :members:
    :undoc-members:
 
diff --git a/pyproject.toml b/pyproject.toml
index 4ace332fd..eba475b4e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -61,7 +61,6 @@ optional-dependencies.dev = [
     "doc8==2.0.0",
     "doccmd==2026.3.26.2",
     "docker==7.1.0",
-    "enum-tools[sphinx]==0.13.0",
     "freezegun==1.5.5",
     "furo==2025.12.19",
     "interrogate==1.7.0",
@@ -88,13 +87,13 @@ optional-dependencies.dev = [
     # use it to lint shell commands in GitHub workflow files.
     "shellcheck-py==0.11.0.1",
     "shfmt-py==3.12.0.2",
-    "sphinx==8.2.3",
+    "sphinx==9.1.0",
     "sphinx-copybutton==0.5.2",
     "sphinx-lint==1.0.2",
     "sphinx-paramlinks==0.6",
     "sphinx-pyproject==0.3.0",
     "sphinx-substitution-extensions==2026.1.12",
-    "sphinx-toolbox==4.1.2",
+    "sphinx-toolbox==4.2.0rc1",
     "sphinxcontrib-httpdomain==2.0.0",
     "sphinxcontrib-spelling==8.0.2",
     "sybil==10.0.1",
@@ -427,6 +426,7 @@ ignore_names = [
     "autoclass_content",
     "autoclass_content",
     "autodoc_member_order",
+    "autodoc_use_legacy_class_based",
     "copybutton_exclude",
     "extensions",
     "html_show_copyright",