[3.9] bpo-40204: Pin Sphinx version to 2.3.1 in ``Doc/Makefile``. (GH-21141)
diff --git a/Doc/Makefile b/Doc/Makefile
index 05361f2ee2c82f..b8ca1edfbc60a5 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -143,7 +143,7 @@ clean:
 venv:
 	$(PYTHON) -m venv $(VENVDIR)
 	$(VENVDIR)/bin/python3 -m pip install -U pip setuptools
-	$(VENVDIR)/bin/python3 -m pip install -U Sphinx==2.2.0 blurb python-docs-theme
+	$(VENVDIR)/bin/python3 -m pip install -U Sphinx==2.3.1 blurb python-docs-theme
 	@echo "The venv has been created in the $(VENVDIR) directory"
 
 dist:
diff --git a/Misc/NEWS.d/next/Build/2020-06-25-06-59-13.bpo-40204.GpD04D.rst b/Misc/NEWS.d/next/Build/2020-06-25-06-59-13.bpo-40204.GpD04D.rst
new file mode 100644
index 00000000000000..25a6d751e5f45c
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2020-06-25-06-59-13.bpo-40204.GpD04D.rst
@@ -0,0 +1 @@
+Pin Sphinx version to 2.3.1 in ``Doc/Makefile``.

(cherry picked from commit 589e8fe07934a8585d6c5c31d12ae5f766b8fec7)


Co-authored-by: Ned Deily <nad@python.org>

<!-- issue-number: [bpo-40204](https://bugs.python.org/issue40204) -->
https://bugs.python.org/issue40204
<!-- /issue-number -->
