heroku · edmorley · Jan 8, 2025 · Jan 7, 2025
@@ -58,8 +58,7 @@ jobs:
         run: aws s3 sync ./upload "s3://${S3_BUCKET}"
 
   heroku-22:
-    # On Heroku-22 we only support Python 3.9+.
-    if: inputs.stack == 'heroku-22' || (inputs.stack == 'auto' && !startsWith(inputs.python_version,'3.8.'))
+    if: inputs.stack == 'heroku-22' || inputs.stack == 'auto'
     runs-on: pub-hk-ubuntu-24.04-xlarge
     env:
       STACK_VERSION: "22"
@@ -80,8 +79,7 @@ jobs:
         run: aws s3 sync ./upload "s3://${S3_BUCKET}"
 
   heroku-24:
-    # On Heroku-24 we only support Python 3.9+.
-    if: inputs.stack == 'heroku-24' || (inputs.stack == 'auto' && !startsWith(inputs.python_version,'3.8.'))
+    if: inputs.stack == 'heroku-24' || inputs.stack == 'auto'
     strategy:
       fail-fast: false
       matrix:

@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+- Added a deprecation warning for Python 3.9. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
+- Removed support for Python 3.8. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
+- Improved the error messages shown for EOL or unrecognised major Python versions. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
 
 ## [v273] - 2025-01-03
 

@@ -49,7 +49,6 @@ The supported Python versions are:
 These Python versions are deprecated on Heroku:
 
 - Python 3.9
-- Python 3.8 (only available on the [Heroku-20](https://devcenter.heroku.com/articles/heroku-20-stack) stack)
 
 Python versions older than those listed above are no longer supported, since they have reached
 end-of-life [upstream](https://devguide.python.org/versions/#supported-versions).

@@ -194,7 +194,7 @@ meta_time "package_manager_install_duration" "${package_manager_install_start_ti
 # Installs the sqlite3 dev headers and sqlite3 binary but not the
 # libsqlite3-0 library since that exists in the base image.
 # We skip this step on Python 3.13 or when using Poetry, as a first step towards removing this feature.
-if [[ "${python_major_version}" == +(3.8|3.9|3.10|3.11|3.12) && "${package_manager}" != "poetry" ]]; then
+if [[ "${python_major_version}" == +(3.9|3.10|3.11|3.12) && "${package_manager}" != "poetry" ]]; then
 	install_sqlite_start_time=$(nowms)
 	source "${BUILDPACK_DIR}/bin/steps/sqlite3"
 	buildpack_sqlite3_install

@@ -14,7 +14,7 @@ PYTHON_URL="${S3_BASE_URL}/python-${python_full_version}-ubuntu-${UBUNTU_VERSION
 # 1. It's a Python major version we've deprecated and so is only available on older stacks (i.e: Python 3.8).
 # 2. If an exact Python version was requested and the patch version doesn't exist (e.g. 3.12.999).
 # 3. The user has pinned to an older buildpack version and the S3 bucket location or layout has changed since.
-# TODO: Update this message to be more specific once Python 3.8 support is dropped.
+# TODO: Update this message to be more specific now that Python 3.8 support has been removed, and so (1) can no longer occur.
 if ! curl --output /dev/null --silent --head --fail --retry 3 --retry-connrefused --connect-timeout 10 "${PYTHON_URL}"; then
 	output::error <<-EOF
 		Error: Python ${python_full_version} isn't available for this stack (${STACK}).
@@ -74,18 +74,22 @@ function warn_if_patch_update_available() {
 # We wait until now to display outdated Python version warnings, since we only want to show them
 # if there weren't any errors with the version to avoid adding noise to the error messages.
 # TODO: Move this into lib/ as part of the warnings refactor.
-if [[ "${python_major_version}" == "3.8" ]]; then
-	output::warning <<-'EOF'
-		Warning: Support for Python 3.8 is ending soon!
+if [[ "${python_major_version}" == "3.9" ]]; then
+	output::warning <<-EOF
+		Warning: Support for Python 3.9 is ending soon!
 
-		Python 3.8 reached its upstream end-of-life on 7th October 2024, and so
-		no longer receives security updates:
+		Python 3.9 will reach its upstream end-of-life in October 2025,
+		at which point it will no longer receive security updates:
 		https://devguide.python.org/versions/#supported-versions
 
-		Support for Python 3.8 will be removed from this buildpack on 7th January 2025.
+		As such, support for Python 3.9 will be removed from this
+		buildpack on 7th January 2026.
 
-		Upgrade to a newer Python version as soon as possible to keep your app secure.
-		See: https://devcenter.heroku.com/articles/python-runtimes
+		Upgrade to a newer Python version as soon as possible, by
+		changing the version in your ${python_version_origin} file.
+
+		For more information, see:
+		https://devcenter.heroku.com/articles/python-support#supported-python-versions
 	EOF
 fi
 

@@ -21,7 +21,7 @@ function abort() {
 }
 
 case "${STACK:?}" in
-	heroku-22 | heroku-24)
+	heroku-20 | heroku-22 | heroku-24)
 		SUPPORTED_PYTHON_VERSIONS=(
 			"3.9"
 			"3.10"
@@ -30,16 +30,6 @@ case "${STACK:?}" in
 			"3.13"
 		)
 		;;
-	heroku-20)
-		SUPPORTED_PYTHON_VERSIONS=(
-			"3.8"
-			"3.9"
-			"3.10"
-			"3.11"
-			"3.12"
-			"3.13"
-		)
-		;;
 	*)
 		abort "Unsupported stack '${STACK}'!"
 		;;
@@ -63,7 +53,7 @@ case "${PYTHON_MAJOR_VERSION}" in
 		# https://keybase.io/pablogsal/
 		GPG_KEY_FINGERPRINT='A035C8C19219BA821ECEA86B64E628F8D684696D'
 		;;
-	3.8 | 3.9)
+	3.9)
 		# https://keybase.io/ambv/
 		GPG_KEY_FINGERPRINT='E3FF2839C048B25C084DEBE9B26995E310250568'
 		;;
@@ -122,7 +112,7 @@ CONFIGURE_OPTS=(
 	"--with-system-expat"
 )
 
-if [[ "${PYTHON_MAJOR_VERSION}" != +(3.8|3.9) ]]; then
+if [[ "${PYTHON_MAJOR_VERSION}" != +(3.9) ]]; then
 	CONFIGURE_OPTS+=(
 		# Shared builds are beneficial for a number of reasons:
 		# - Reduces the size of the build, since it avoids the duplication between
@@ -147,7 +137,7 @@ if [[ "${PYTHON_MAJOR_VERSION}" != +(3.8|3.9) ]]; then
 	)
 fi
 
-if [[ "${PYTHON_MAJOR_VERSION}" != +(3.8|3.9|3.10) ]]; then
+if [[ "${PYTHON_MAJOR_VERSION}" != +(3.9|3.10) ]]; then
 	CONFIGURE_OPTS+=(
 		# Skip building the test modules, since we remove them after the build anyway.
 		# This feature was added in Python 3.10+, however it wasn't until Python 3.11
@@ -170,7 +160,7 @@ fi
 # - https://github.com/docker-library/python/issues/810
 # We only use `dpkg-buildflags` for Python versions where we build in shared mode (Python 3.9+),
 # since some of the options it enables interferes with the stripping of static libraries.
-if [[ "${PYTHON_MAJOR_VERSION}" == +(3.8|3.9) ]]; then
+if [[ "${PYTHON_MAJOR_VERSION}" == +(3.9) ]]; then
 	EXTRA_CFLAGS=''
 	LDFLAGS='-Wl,--strip-all'
 else
@@ -182,7 +172,7 @@ CPU_COUNT="$(nproc)"
 make -j "${CPU_COUNT}" "EXTRA_CFLAGS=${EXTRA_CFLAGS}" "LDFLAGS=${LDFLAGS}"
 make install
 
-if [[ "${PYTHON_MAJOR_VERSION}" == +(3.8|3.9) ]]; then
+if [[ "${PYTHON_MAJOR_VERSION}" == +(3.9) ]]; then
 	# On older versions of Python we're still building the static library, which has to be
 	# manually stripped since the linker stripping enabled in LDFLAGS doesn't cover them.
 	# We're using `--strip-unneeded` since `--strip-all` would remove the `.symtab` section
@@ -233,7 +223,7 @@ LD_LIBRARY_PATH="${SRC_DIR}" "${SRC_DIR}/python" -m compileall -f --invalidation
 # (e.g. `python -m pydoc`) if needed.
 rm "${INSTALL_DIR}"/bin/{idle,pydoc}*
 # The 2to3 module and entrypoint was removed from the stdlib in Python 3.13.
-if [[ "${PYTHON_MAJOR_VERSION}" == +(3.8|3.9|3.10|3.11|3.12) ]]; then
+if [[ "${PYTHON_MAJOR_VERSION}" == +(3.9|3.10|3.11|3.12) ]]; then
 	rm "${INSTALL_DIR}"/bin/2to3*
 fi
 

@@ -31,7 +31,7 @@ function pip::install_pip_setuptools_wheel() {
 	#   them installed.
 	# - Most of the Python ecosystem has stopped installing them for Python 3.12+ already.
 	# See the Python CNB's removal for more details: https://github.com/heroku/buildpacks-python/pull/243
-	if [[ "${python_major_version}" == +(3.8|3.9|3.10|3.11|3.12) ]]; then
+	if [[ "${python_major_version}" == +(3.9|3.10|3.11|3.12) ]]; then
 		meta_set "setuptools_version" "${SETUPTOOLS_VERSION}"
 		meta_set "wheel_version" "${WHEEL_VERSION}"
 		packages_to_install+=(

@@ -4,13 +4,15 @@
 # however, it helps Shellcheck realise the options under which these functions will run.
 set -euo pipefail
 
-LATEST_PYTHON_3_8="3.8.20"
 LATEST_PYTHON_3_9="3.9.21"
 LATEST_PYTHON_3_10="3.10.16"
 LATEST_PYTHON_3_11="3.11.11"
 LATEST_PYTHON_3_12="3.12.8"
 LATEST_PYTHON_3_13="3.13.1"
 
+OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION=9
+NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION=13
+
 DEFAULT_PYTHON_FULL_VERSION="${LATEST_PYTHON_3_13}"
 DEFAULT_PYTHON_MAJOR_VERSION="${DEFAULT_PYTHON_FULL_VERSION%.*}"
 
@@ -280,7 +282,7 @@ function python_version::resolve_python_version() {
 	local major="${BASH_REMATCH[1]}"
 	local minor="${BASH_REMATCH[2]}"
 
-	if ((major < 3 || (major == 3 && minor < 8))); then
+	if ((major < 3 || (major == 3 && minor < OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION))); then
 		if [[ "${python_version_origin}" == "cached" ]]; then
 			output::error <<-EOF
 				Error: The cached Python version has reached end-of-life.
@@ -292,14 +294,13 @@ function python_version::resolve_python_version() {
 				and is therefore no longer receiving security updates:
 				https://devguide.python.org/versions/#supported-versions
 
-				As such, it is no longer supported by this buildpack.
-
-				Please upgrade to a newer Python version by creating a
-				'.python-version' file that contains a Python version like:
-				${DEFAULT_PYTHON_MAJOR_VERSION}
-
-				For a list of the supported Python versions, see:
+				As such, it's no longer supported by this buildpack:
 				https://devcenter.heroku.com/articles/python-support#supported-python-versions
+
+				Please upgrade to at least Python 3.${OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION} by creating a
+				.python-version file in the root directory of your app,
+				that contains a Python version like:
+				3.${OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION}
 			EOF
 		else
 			output::error <<-EOF
@@ -309,20 +310,18 @@ function python_version::resolve_python_version() {
 				therefore no longer receiving security updates:
 				https://devguide.python.org/versions/#supported-versions
 
-				As such, it is no longer supported by this buildpack.
-
-				Please upgrade to a newer Python version by updating the
-				version configured via the '${python_version_origin}' file.
-
-				For a list of the supported Python versions, see:
+				As such, it's no longer supported by this buildpack:
 				https://devcenter.heroku.com/articles/python-support#supported-python-versions
+
+				Please upgrade to at least Python 3.${OLDEST_SUPPORTED_PYTHON_3_MINOR_VERSION} by changing the
+				version in your ${python_version_origin} file.
 			EOF
 		fi
 		meta_set "failure_reason" "python-version::eol"
 		exit 1
 	fi
 
-	if (((major == 3 && minor > 13) || major >= 4)); then
+	if (((major == 3 && minor > NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION) || major >= 4)); then
 		if [[ "${python_version_origin}" == "cached" ]]; then
 			output::error <<-EOF
 				Error: The cached Python version isn't recognised.
@@ -336,7 +335,14 @@ function python_version::resolve_python_version() {
 				This can occur if you have downgraded the version of the
 				buildpack to an older version.
 
-				Please switch back to a newer version of this buildpack.
+				Please switch back to a newer version of this buildpack:
+				https://devcenter.heroku.com/articles/managing-buildpacks#view-your-buildpacks
+				https://devcenter.heroku.com/articles/managing-buildpacks#classic-buildpacks-references
+
+				Alternatively, request an older Python version by creating
+				a .python-version file in the root directory of your app,
+				that contains a Python version like:
+				3.${NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION}
 			EOF
 		else
 			output::error <<-EOF
@@ -350,12 +356,12 @@ function python_version::resolve_python_version() {
 				https://devcenter.heroku.com/articles/python-support#supported-python-versions
 
 				If it has, make sure that you are using the latest version
-				of this buildpack, and have not pinned to an older release:
+				of this buildpack, and haven't pinned to an older release:
 				https://devcenter.heroku.com/articles/managing-buildpacks#view-your-buildpacks
 				https://devcenter.heroku.com/articles/managing-buildpacks#classic-buildpacks-references
 
-				Otherwise, switch to a supported version (such as Python ${DEFAULT_PYTHON_MAJOR_VERSION})
-				by updating the version configured via the '${python_version_origin}' file.
+				Otherwise, switch to a supported version (such as Python 3.${NEWEST_SUPPORTED_PYTHON_3_MINOR_VERSION})
+				by changing the version in your ${python_version_origin} file.
 			EOF
 		fi
 		meta_set "failure_reason" "python-version::unknown-major"
@@ -366,7 +372,6 @@ function python_version::resolve_python_version() {
 	# Otherwise map major version specifiers to the latest patch release.
 	case "${requested_python_version}" in
 		*.*.*) echo "${requested_python_version}" ;;
-		3.8) echo "${LATEST_PYTHON_3_8}" ;;
 		3.9) echo "${LATEST_PYTHON_3_9}" ;;
 		3.10) echo "${LATEST_PYTHON_3_10}" ;;
 		3.11) echo "${LATEST_PYTHON_3_11}" ;;

@@ -9,4 +9,4 @@ typing-extensions = "*"
 [dev-packages]
 
 [requires]
-python_version = "3.7"
+python_version = "3.8"
@@ -4,5 +4,5 @@
 # So are empty lines, and leading/trailing whitespace.
 
 
-  3.7  
+  3.8  
 
@@ -1 +1 @@
-3.9.0
+3.10.0
@@ -1 +1 @@
-python-3.8.0
+python-3.9.0
@@ -80,6 +80,22 @@
           remote: -----> Using Python 3.9.0 specified in Pipfile.lock
           remote: -----> Installing Python 3.9.0
           remote: 
+          remote:  !     Warning: Support for Python 3.9 is ending soon!
+          remote:  !     
+          remote:  !     Python 3.9 will reach its upstream end-of-life in October 2025,
+          remote:  !     at which point it will no longer receive security updates:
+          remote:  !     https://devguide.python.org/versions/#supported-versions
+          remote:  !     
+          remote:  !     As such, support for Python 3.9 will be removed from this
+          remote:  !     buildpack on 7th January 2026.
+          remote:  !     
+          remote:  !     Upgrade to a newer Python version as soon as possible, by
+          remote:  !     changing the version in your Pipfile.lock file.
+          remote:  !     
+          remote:  !     For more information, see:
+          remote:  !     https://devcenter.heroku.com/articles/python-support#supported-python-versions
+          remote: 
+          remote: 
           remote:  !     Warning: A Python security update is available!
           remote:  !     
           remote:  !     Upgrade as soon as possible to: Python #{LATEST_PYTHON_3_9}
@@ -266,21 +282,19 @@
       app.deploy do |app|
         expect(clean_output(app.output)).to match(Regexp.new(<<~OUTPUT))
           remote: -----> Python app detected
-          remote: -----> Using Python 3.7 specified in Pipfile.lock
+          remote: -----> Using Python 3.8 specified in Pipfile.lock
           remote: 
           remote:  !     Error: The requested Python version has reached end-of-life.
           remote:  !     
-          remote:  !     Python 3.7 has reached its upstream end-of-life, and is
+          remote:  !     Python 3.8 has reached its upstream end-of-life, and is
           remote:  !     therefore no longer receiving security updates:
           remote:  !     https://devguide.python.org/versions/#supported-versions
           remote:  !     
-          remote:  !     As such, it is no longer supported by this buildpack.
-          remote:  !     
-          remote:  !     Please upgrade to a newer Python version by updating the
-          remote:  !     version configured via the 'Pipfile.lock' file.
-          remote:  !     
-          remote:  !     For a list of the supported Python versions, see:
+          remote:  !     As such, it's no longer supported by this buildpack:
           remote:  !     https://devcenter.heroku.com/articles/python-support#supported-python-versions
+          remote:  !     
+          remote:  !     Please upgrade to at least Python 3.9 by changing the
+          remote:  !     version in your Pipfile.lock file.
           remote: 
           remote:  !     Push rejected, failed to compile Python app.
         OUTPUT
Original file line number	Diff line number	Diff line change
Expand Up		@@ -4,5 +4,5 @@
		# So are empty lines, and leading/trailing whitespace.


		3.7
		3.8