diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 8e33dff..85facf0 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -16,10 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.12", "3.11", "3.10", "3.9"]
-    env:
-      PYTHONUNBUFFERED: 1
-      PYTHONWARNINGS: always
+        python-version: ["3.12", "3.11", "3.10"]
     steps:
     - name: Checkout
       run: |
@@ -34,7 +31,7 @@ jobs:
       with:
         python-version: '${{ matrix.python-version }}'
         cache: 'pip' # caching pip dependencies
-        cache-dependency-path: '**/requirements.dev.txt'
+        cache-dependency-path: '**/requirements.*.txt'
 
     - name: 'Bootstrap app venv'
       # The first CLI call will create the .venv
@@ -59,6 +56,9 @@ jobs:
         ./dev-cli.py safety
 
     - name: 'Run tests with Python v${{ matrix.python-version }}'
+      env:
+        PYTHONUNBUFFERED: 1
+        PYTHONWARNINGS: always
       run: |
         ./dev-cli.py coverage
 
diff --git a/README.md b/README.md
index 159c424..c5268e0 100644
--- a/README.md
+++ b/README.md
@@ -255,7 +255,7 @@ Usage: ./cli.py format-file [OPTIONS] FILE_PATH
 ╭─ Options ────────────────────────────────────────────────────────────────────────────────────────╮
 │ --py-version                     TEXT     Fallback Python version for darker/pyupgrade, if       │
 │                                           version is not defined in pyproject.toml               │
-│                                           [default: 3.9]                                         │
+│                                           [default: 3.10]                                        │
 │ --max-line-length            -l  INTEGER  Fallback max. line length for darker/isort etc., if    │
 │                                           not defined in .editorconfig                           │
 │                                           [default: 119]                                         │
@@ -332,6 +332,10 @@ See also git tags: https://github.com/jedie/manageprojects/tags
 
 [comment]: <> (✂✂✂ auto generated history start ✂✂✂)
 
+* [v0.17.0](https://github.com/jedie/manageprojects/compare/v0.16.2...v0.17.0)
+  * 2023-12-21 - Unify BASE_PATH / PACKAGE_ROOT etc.
+  * 2023-12-21 - Apply manageprojects updates: Skip Python 3.9 support
+  * 2023-12-21 - Update requirements
 * [v0.16.2](https://github.com/jedie/manageprojects/compare/v0.16.1...v0.16.2)
   * 2023-12-16 - Update pre-commit-config
   * 2023-12-16 - Skip test_readme_history() on CI
@@ -344,11 +348,11 @@ See also git tags: https://github.com/jedie/manageprojects/tags
   * 2023-12-02 - Use code style tooling from cli-base-utilities
   * 2023-12-01 - Apply https://github.com/jedie/cookiecutter_templates updates
   * 2023-12-01 - Use: cli_base.cli_tools.test_utils.logs.AssertLogs
-* [v0.15.4](https://github.com/jedie/manageprojects/compare/v0.15.3...v0.15.4)
-  * 2023-11-27 - Use "flake8-bugbear", too.
 
 <details><summary>Expand older history entries ...</summary>
 
+* [v0.15.4](https://github.com/jedie/manageprojects/compare/v0.15.3...v0.15.4)
+  * 2023-11-27 - Use "flake8-bugbear", too.
 * [v0.15.3](https://github.com/jedie/manageprojects/compare/v0.15.2...v0.15.3)
   * 2023-11-09 - Bugfix "reverse" if context contains a list
   * 2023-11-07 - Update requirements
diff --git a/cli.py b/cli.py
index 4043912..175bb51 100755
--- a/cli.py
+++ b/cli.py
@@ -8,6 +8,7 @@
 """
 
 import hashlib
+import shlex
 import subprocess
 import sys
 import venv
@@ -32,7 +33,7 @@ def print_no_pip_error():
         sys.exit(-1)
 
 
-assert sys.version_info >= (3, 9), 'Python version is too old!'
+assert sys.version_info >= (3, 10), f'Python version {sys.version_info} is too old!'
 
 
 if sys.platform == 'win32':  # wtf
@@ -77,7 +78,7 @@ def venv_up2date():
 
 
 def verbose_check_call(*popen_args):
-    print(f'\n+ {" ".join(str(arg) for arg in popen_args)}\n')
+    print(f'\n+ {shlex.join(str(arg) for arg in popen_args)}\n')
     return subprocess.check_call(popen_args)
 
 
diff --git a/dev-cli.py b/dev-cli.py
index 3449618..6f46420 100755
--- a/dev-cli.py
+++ b/dev-cli.py
@@ -8,6 +8,7 @@
 """
 
 import hashlib
+import shlex
 import subprocess
 import sys
 import venv
@@ -32,7 +33,7 @@ def print_no_pip_error():
         sys.exit(-1)
 
 
-assert sys.version_info >= (3, 9), 'Python version is too old!'
+assert sys.version_info >= (3, 10), f'Python version {sys.version_info} is too old!'
 
 
 if sys.platform == 'win32':  # wtf
@@ -77,7 +78,7 @@ def venv_up2date():
 
 
 def verbose_check_call(*popen_args):
-    print(f'\n+ {" ".join(str(arg) for arg in popen_args)}\n')
+    print(f'\n+ {shlex.join(str(arg) for arg in popen_args)}\n')
     return subprocess.check_call(popen_args)
 
 
diff --git a/manageprojects/__init__.py b/manageprojects/__init__.py
index 4ff16de..6a1c5da 100644
--- a/manageprojects/__init__.py
+++ b/manageprojects/__init__.py
@@ -3,5 +3,5 @@
     Manage Python / Django projects
 """
 
-__version__ = '0.16.2'
+__version__ = '0.17.0'
 __author__ = 'Jens Diemer <mamageprojects@jensdiemer.de>'
diff --git a/manageprojects/cli/cli_app.py b/manageprojects/cli/cli_app.py
index 5311ded..972487e 100644
--- a/manageprojects/cli/cli_app.py
+++ b/manageprojects/cli/cli_app.py
@@ -6,10 +6,9 @@
 import subprocess
 import sys
 from pathlib import Path
-from typing import Optional
 
 import rich_click as click
-from bx_py_utils.path import assert_is_dir, assert_is_file
+from bx_py_utils.path import assert_is_dir
 from cli_base.cli_tools.subprocess_utils import verbose_check_call
 from cli_base.cli_tools.verbosity import OPTION_KWARGS_VERBOSE
 from cli_base.cli_tools.version_info import print_version
@@ -39,9 +38,6 @@
 logger = logging.getLogger(__name__)
 
 
-PACKAGE_ROOT = Path(manageprojects.__file__).parent.parent
-assert_is_file(PACKAGE_ROOT / 'pyproject.toml')
-
 OPTION_ARGS_DEFAULT_TRUE = dict(is_flag=True, show_default=True, default=True)
 OPTION_ARGS_DEFAULT_FALSE = dict(is_flag=True, show_default=True, default=False)
 ARGUMENT_EXISTING_DIR = dict(
@@ -116,12 +112,12 @@ def cli():
 def start_project(
     template: str,
     output_dir: Path,
-    directory: Optional[str],
-    checkout: Optional[str],
+    directory: str | None,
+    checkout: str | None,
     input: bool,
     replay: bool,
-    password: Optional[str],
-    config_file: Optional[Path],
+    password: str | None,
+    config_file: Path | None,
 ):
     """
     Start a new "managed" project via a CookieCutter Template.
@@ -199,8 +195,8 @@ def start_project(
 def update_project(
     project_path: Path,
     overwrite: bool,
-    password: Optional[str],
-    config_file: Optional[Path],
+    password: str | None,
+    config_file: Path | None,
     input: bool,
     cleanup: bool,
 ):
@@ -250,9 +246,9 @@ def clone_project(
     project_path: Path,
     output_dir: Path,
     input: bool,
-    checkout: Optional[str] = None,
-    password: Optional[str] = None,
-    config_file: Optional[Path] = None,
+    checkout: str | None = None,
+    password: str | None = None,
+    config_file: Path | None = None,
 ):
     """
     Clone existing project by replay the cookiecutter template in a new directory.
diff --git a/manageprojects/cli/dev.py b/manageprojects/cli/dev.py
index 27cfee8..489e7e5 100644
--- a/manageprojects/cli/dev.py
+++ b/manageprojects/cli/dev.py
@@ -19,13 +19,14 @@
 
 import manageprojects
 from manageprojects import constants
+from manageprojects.constants import BASE_PATH
 from manageprojects.utilities.publish import publish_package
 
 
 logger = logging.getLogger(__name__)
 
 
-PACKAGE_ROOT = Path(manageprojects.__file__).parent.parent
+PACKAGE_ROOT = BASE_PATH.parent
 assert_is_file(PACKAGE_ROOT / 'pyproject.toml')
 
 OPTION_ARGS_DEFAULT_TRUE = dict(is_flag=True, show_default=True, default=True)
diff --git a/manageprojects/constants.py b/manageprojects/constants.py
index a541791..323eafd 100644
--- a/manageprojects/constants.py
+++ b/manageprojects/constants.py
@@ -1,6 +1,8 @@
 import sys
 from pathlib import Path
 
+import manageprojects
+
 
 INITIAL_REVISION = 'initial_revision'
 INITIAL_DATE = 'initial_date'
@@ -24,7 +26,8 @@
         ]
     )
 )
-FORMAT_PY_FILE_DEFAULT_MIN_PYTON_VERSION = '3.9'
+FORMAT_PY_FILE_DEFAULT_MIN_PYTON_VERSION = '3.10'
 FORMAT_PY_FILE_DEFAULT_MAX_LINE_LENGTH = 119
 
 PY_BIN_PATH = Path(sys.executable).parent
+BASE_PATH = Path(manageprojects.__file__).parent
diff --git a/manageprojects/tests/base.py b/manageprojects/tests/base.py
index a36a77e..030d9d4 100644
--- a/manageprojects/tests/base.py
+++ b/manageprojects/tests/base.py
@@ -7,11 +7,9 @@
 
 from bx_py_utils.path import assert_is_file
 
-import manageprojects
 from manageprojects.utilities.pyproject_toml import TomlDocument, get_toml_document
 
 
-PROJECT_PATH = Path(manageprojects.__file__).parent.parent
 GIT_BIN_PARENT = Path(shutil.which('git')).parent
 
 
diff --git a/manageprojects/tests/test_cli.py b/manageprojects/tests/test_cli.py
index 624e4f6..03e4077 100644
--- a/manageprojects/tests/test_cli.py
+++ b/manageprojects/tests/test_cli.py
@@ -4,7 +4,8 @@
 from unittest.mock import MagicMock
 
 from manageprojects.cli import cli_app
-from manageprojects.cli.cli_app import PACKAGE_ROOT, start_project, update_project
+from manageprojects.cli.cli_app import start_project, update_project
+from manageprojects.cli.dev import PACKAGE_ROOT
 from manageprojects.cli.dev import cli as dev_cli
 from manageprojects.constants import PY_BIN_PATH
 from manageprojects.data_classes import CookiecutterResult
diff --git a/manageprojects/tests/test_format_file.py b/manageprojects/tests/test_format_file.py
index 2e482ea..dfc0005 100644
--- a/manageprojects/tests/test_format_file.py
+++ b/manageprojects/tests/test_format_file.py
@@ -5,6 +5,7 @@
 from cli_base.cli_tools.test_utils.logs import AssertLogs
 from packaging.version import Version
 
+from manageprojects.cli.dev import PACKAGE_ROOT
 from manageprojects.constants import PY_BIN_PATH
 from manageprojects.format_file import (
     Config,
@@ -17,7 +18,7 @@
     get_pyproject_info,
 )
 from manageprojects.test_utils.subprocess import SimpleRunReturnCallback, SubprocessCallMock
-from manageprojects.tests.base import GIT_BIN_PARENT, PROJECT_PATH
+from manageprojects.tests.base import GIT_BIN_PARENT
 from manageprojects.utilities.temp_path import TemporaryDirectory
 
 
@@ -111,9 +112,9 @@ def test_get_pyproject_info(self):
         self.assertEqual(
             get_pyproject_info(file_path=Path(__file__), default_min_py_version='3.7'),
             PyProjectInfo(
-                pyproject_toml_path=PROJECT_PATH / 'pyproject.toml',
-                py_min_ver=Version('3.9'),
-                raw_py_ver_req='>=3.9,<4',
+                pyproject_toml_path=PACKAGE_ROOT / 'pyproject.toml',
+                py_min_ver=Version('3.10'),
+                raw_py_ver_req='>=3.10',
             ),
         )
 
@@ -129,11 +130,11 @@ def test_get_config(self):
             self.assertEqual(
                 config,
                 Config(
-                    git_info=GitInfo(cwd=PROJECT_PATH, main_branch_name='main'),
+                    git_info=GitInfo(cwd=PACKAGE_ROOT, main_branch_name='main'),
                     pyproject_info=PyProjectInfo(
-                        pyproject_toml_path=PROJECT_PATH / 'pyproject.toml',
-                        py_min_ver=Version('3.9'),
-                        raw_py_ver_req='>=3.9,<4',
+                        pyproject_toml_path=PACKAGE_ROOT / 'pyproject.toml',
+                        py_min_ver=Version('3.10'),
+                        raw_py_ver_req='>=3.10',
                     ),
                     max_line_length=119,
                 ),
@@ -146,7 +147,7 @@ def test_get_config(self):
                     Config(
                         git_info=None,
                         pyproject_info=PyProjectInfo(
-                            py_min_ver=Version('3.9'), pyproject_toml_path=None, raw_py_ver_req=None
+                            py_min_ver=Version('3.10'), pyproject_toml_path=None, raw_py_ver_req=None
                         ),
                         max_line_length=119,
                     ),
@@ -173,7 +174,7 @@ def test_format_one_file(self):
                 [
                     '.../pyupgrade',
                     '--exit-zero-even-if-changed',
-                    '--py39-plus',
+                    '--py310-plus',
                     'manageprojects/tests/test_format_file.py',
                 ],
                 [
@@ -201,7 +202,7 @@ def test_format_one_file(self):
                     '--line-length',
                     '119',
                     '--target-version',
-                    'py39',
+                    'py310',
                     'manageprojects/tests/test_format_file.py',
                 ],
                 ['.../flake8', '--max-line-length', '119', 'manageprojects/tests/test_format_file.py'],
@@ -238,7 +239,7 @@ def test_format_one_file(self):
                 [
                     '.../pyupgrade',
                     '--exit-zero-even-if-changed',
-                    '--py39-plus',
+                    '--py310-plus',
                     'manageprojects/tests/test_format_file.py',
                 ],
                 ['.../autoflake', '--in-place', 'manageprojects/tests/test_format_file.py'],
diff --git a/manageprojects/tests/test_project_setup.py b/manageprojects/tests/test_project_setup.py
index a9dc7be..8b994f5 100644
--- a/manageprojects/tests/test_project_setup.py
+++ b/manageprojects/tests/test_project_setup.py
@@ -6,7 +6,7 @@
 from packaging.version import Version
 
 from manageprojects import __version__
-from manageprojects.cli.cli_app import PACKAGE_ROOT
+from manageprojects.cli.dev import PACKAGE_ROOT
 from manageprojects.test_utils.project_setup import check_editor_config, get_py_max_line_length
 
 
diff --git a/manageprojects/tests/test_readme.py b/manageprojects/tests/test_readme.py
index b02c845..999f483 100644
--- a/manageprojects/tests/test_readme.py
+++ b/manageprojects/tests/test_readme.py
@@ -2,7 +2,8 @@
 from bx_py_utils.path import assert_is_file
 
 from manageprojects import constants
-from manageprojects.cli.cli_app import PACKAGE_ROOT, cli
+from manageprojects.cli.cli_app import cli
+from manageprojects.cli.dev import PACKAGE_ROOT
 from manageprojects.cli.dev import cli as dev_cli
 from manageprojects.test_utils.click_cli_utils import invoke_click
 from manageprojects.tests.base import BaseTestCase
diff --git a/manageprojects/tests/test_utilities_pyproject_toml.py b/manageprojects/tests/test_utilities_pyproject_toml.py
index 358f21d..96bbb1d 100644
--- a/manageprojects/tests/test_utilities_pyproject_toml.py
+++ b/manageprojects/tests/test_utilities_pyproject_toml.py
@@ -5,7 +5,7 @@
 from bx_py_utils.test_utils.datetime import parse_dt
 from cli_base.cli_tools.test_utils.logs import AssertLogs
 
-import manageprojects
+from manageprojects.constants import BASE_PATH
 from manageprojects.data_classes import ManageProjectsMeta
 from manageprojects.tests.base import BaseTestCase
 from manageprojects.utilities.pyproject_toml import PyProjectToml, find_pyproject_toml
@@ -268,7 +268,7 @@ def test_expand_existing_toml(self):
         logs.assert_in('Read existing pyproject.toml')
 
     def test_find_pyproject_toml(self):
-        own_pyproject_toml = Path(manageprojects.__file__).parent.parent / 'pyproject.toml'
+        own_pyproject_toml = BASE_PATH.parent / 'pyproject.toml'
         assert_is_file(own_pyproject_toml)
         self.assertEqual(find_pyproject_toml(file_path=Path(__file__)), own_pyproject_toml)
 
diff --git a/pyproject.toml b/pyproject.toml
index cdaae18..5650511 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,7 +7,7 @@ readme = "README.md"
 authors = [
     {name = 'Jens Diemer', email = 'mamageprojects@jensdiemer.de'}
 ]
-requires-python = ">=3.9,<4"
+requires-python = ">=3.10"
 dependencies = [
     "cookiecutter>=2.4.0",  # https://github.com/cookiecutter/cookiecutter
     "tomlkit",
@@ -28,7 +28,7 @@ dependencies = [
     "codespell",  # https://github.com/codespell-project/codespell
     "mypy",  # https://github.com/python/mypy
 
-    "cli-base-utilities>=0.7.0rc2",  # https://github.com/jedie/cli-base-utilities
+    "cli-base-utilities",  # https://github.com/jedie/cli-base-utilities
     "click",  # https://github.com/pallets/click/
     "rich-click",  # https://github.com/ewels/rich-click
     "rich",  # https://github.com/Textualize/rich
@@ -125,7 +125,7 @@ exclude_lines = [
 legacy_tox_ini = """
 [tox]
 isolated_build = True
-envlist = py{312,311,310,39}
+envlist = py{312,311,310}
 skip_missing_interpreters = True
 
 [testenv]
@@ -168,6 +168,7 @@ applied_migrations = [
     "be3f649", # 2023-08-22T19:36:57+02:00
     "385f654", # 2023-10-08T21:09:24+02:00
     "d1ed4b1", # 2023-12-01T21:41:29+01:00
+    "c538ae7", # 2023-12-21T20:21:58+01:00
 ]
 
 [manageprojects.cookiecutter_context.cookiecutter]
diff --git a/requirements.dev.txt b/requirements.dev.txt
index 1f2cb83..0279029 100644
--- a/requirements.dev.txt
+++ b/requirements.dev.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.10
+# This file is autogenerated by pip-compile with Python 3.11
 # by the following command:
 #
 #    ./dev-cli.py update
@@ -97,9 +97,7 @@ astor==0.8.1 \
 async-timeout==4.0.3 \
     --hash=sha256:4640d96be84d82d02ed59ea2b7105a0f7b33abe8703703cd0ab0bf87c427522f \
     --hash=sha256:7405140ff1230c310e51dc27b3145b9092d659ce68ff733fb0cefe3ee42be028
-    # via
-    #   aiohttp
-    #   cli-base-utilities
+    # via cli-base-utilities
 attrs==23.1.0 \
     --hash=sha256:1f28b4522cdc2fb4256ac1a020c78acf9cba2c6b461ccd2c126f3aa8e8335d04 \
     --hash=sha256:6279836d581513a26f1bf235f9acd333bc9115683f14f7e8fae46c98fc50e015
@@ -1047,19 +1045,9 @@ tomli==2.0.1 \
     --hash=sha256:939de3e7a6161af0c887ef91b7d41a53e7c5a1ca976325f429cb46ea9bc30ecc \
     --hash=sha256:de526c12914f0c550d15924c62d72abc48d6fe7364aa87328337a31007fe8a4f
     # via
-    #   autoflake
-    #   autopep8
-    #   black
-    #   build
     #   cli-base-utilities
-    #   dparse
     #   flynt
     #   manageprojects (pyproject.toml)
-    #   mypy
-    #   pip-tools
-    #   pyproject-api
-    #   pyproject-hooks
-    #   tox
 tomlkit==0.12.3 \
     --hash=sha256:75baf5012d06501f07bee5bf8e801b9f343e7aac5a92581f20f80ce632e6b5a4 \
     --hash=sha256:b0a645a9156dc7cb5d3a1f0d4bab66db287fcb8e0430bdd4664a095ea16414ba
@@ -1082,7 +1070,6 @@ typing-extensions==4.9.0 \
     --hash=sha256:23478f88c37f27d76ac8aee6c905017a143b0b1b886c3c9f66bc2fd94f9f5783 \
     --hash=sha256:af72aea155e91adfc61c3ae9e0e342dbc0cba726d6cba4b6c72c1f34e47291cd
     # via
-    #   black
     #   mypy
     #   rich-click
 urllib3==2.1.0 \
diff --git a/requirements.txt b/requirements.txt
index 5c2b888..a47f58f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.10
+# This file is autogenerated by pip-compile with Python 3.11
 # by the following command:
 #
 #    ./dev-cli.py update
@@ -97,9 +97,7 @@ astor==0.8.1 \
 async-timeout==4.0.3 \
     --hash=sha256:4640d96be84d82d02ed59ea2b7105a0f7b33abe8703703cd0ab0bf87c427522f \
     --hash=sha256:7405140ff1230c310e51dc27b3145b9092d659ce68ff733fb0cefe3ee42be028
-    # via
-    #   aiohttp
-    #   cli-base-utilities
+    # via cli-base-utilities
 attrs==23.1.0 \
     --hash=sha256:1f28b4522cdc2fb4256ac1a020c78acf9cba2c6b461ccd2c126f3aa8e8335d04 \
     --hash=sha256:6279836d581513a26f1bf235f9acd333bc9115683f14f7e8fae46c98fc50e015
@@ -706,12 +704,8 @@ tomli==2.0.1 \
     --hash=sha256:939de3e7a6161af0c887ef91b7d41a53e7c5a1ca976325f429cb46ea9bc30ecc \
     --hash=sha256:de526c12914f0c550d15924c62d72abc48d6fe7364aa87328337a31007fe8a4f
     # via
-    #   autoflake
-    #   autopep8
-    #   black
     #   cli-base-utilities
     #   flynt
-    #   mypy
 tomlkit==0.12.3 \
     --hash=sha256:75baf5012d06501f07bee5bf8e801b9f343e7aac5a92581f20f80ce632e6b5a4 \
     --hash=sha256:b0a645a9156dc7cb5d3a1f0d4bab66db287fcb8e0430bdd4664a095ea16414ba
@@ -726,7 +720,6 @@ typing-extensions==4.9.0 \
     --hash=sha256:23478f88c37f27d76ac8aee6c905017a143b0b1b886c3c9f66bc2fd94f9f5783 \
     --hash=sha256:af72aea155e91adfc61c3ae9e0e342dbc0cba726d6cba4b6c72c1f34e47291cd
     # via
-    #   black
     #   mypy
     #   rich-click
 urllib3==2.1.0 \