diff --git a/CHANGES.rst b/CHANGES.rst
index 081b82478..2c4a937e1 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -18,6 +18,9 @@ Removed
 -------
 - **Backwards incompatible change:** Baseline linting support (``-L``/``--lint`` option)
   has been removed. Use the Graylint_ tool instead.
+- In the Darker configuration file under ``[tool.darker]``, the Black configuration
+  options ``skip_string_normalization`` and ``skip_magic_trailing_comma`` are no longer
+  valid. Use ``[tool.black]`` instead.
 
 Fixed
 -----
diff --git a/README.rst b/README.rst
index ecf3c331a..7acfc0d10 100644
--- a/README.rst
+++ b/README.rst
@@ -448,8 +448,9 @@ command line options
 
 *New in version 1.7.0:* The ``-f`` / ``--flynt`` command line option
 
-*New in version 2.1.1:* In ``[tool.darker]``, deprecate the the Black options
-``skip_string_normalization`` and ``skip_magic_trailing_comma``
+*New in version 3.0.0:* In ``[tool.darker]``, remove the the Black options
+``skip_string_normalization`` and ``skip_magic_trailing_comma`` (previously deprecated
+in version 2.1.1)
 
 *New in version 3.0.0:* Removed the ``-L`` / ``--lint`` functionality and moved it into
 the Graylint_ package. Also removed ``lint =``, ``skip_string_normalization =`` and
diff --git a/constraints-oldest.txt b/constraints-oldest.txt
index fc3d5b986..70d16afb2 100644
--- a/constraints-oldest.txt
+++ b/constraints-oldest.txt
@@ -20,4 +20,5 @@ ruamel.yaml==0.17.21
 toml==0.10.0
 twine==2.0.0
 types-toml==0.10.4
+typing_extensions==4.0.1
 wheel==0.21.0
diff --git a/pyproject.toml b/pyproject.toml
index 3c30c6d83..4cf7b7edc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,9 +44,14 @@ select = ["ALL"]
 ignore = [
     "A002",  # builtin-argument-shadowing
     "ANN101",  # Missing type annotation for `self` in method
+    "COM812",  # Trailing comma missing
     "D203",  # One blank line required before class docstring
     "D213",  # Multi-line docstring summary should start at the second line
     "D400",  # First line should end with a period (duplicates D415)
+
+    # Remove these when support for Python 3.8 is dropped:
+    "UP006",  # Use `xyz` instead of `Xyz` for type annotation
+    "UP007",  # Use `X | Y` for type annotations
 ]
 
 [tool.ruff.lint.per-file-ignores]
diff --git a/setup.cfg b/setup.cfg
index b2c10bc6a..ca689f2fa 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -31,6 +31,7 @@ install_requires =
     black>=22.3.0
     darkgraylib~=2.0.1
     toml>=0.10.0
+    typing_extensions>=4.0.1
 # NOTE: remember to keep `.github/workflows/python-package.yml` in sync
 #       with the minimum required Python version
 python_requires = >=3.8
diff --git a/src/darker/__main__.py b/src/darker/__main__.py
index 9d598379a..4669a510e 100644
--- a/src/darker/__main__.py
+++ b/src/darker/__main__.py
@@ -490,7 +490,7 @@ def main(  # noqa: C901,PLR0912,PLR0915
     # Make sure there aren't invalid option combinations after merging configuration and
     # command line options.
     OutputMode.validate_diff_stdout(args.diff, args.stdout)
-    OutputMode.validate_stdout_src(args.stdout, args.src, args.stdin_filename)
+    OutputMode.validate_stdout_src(args.src, args.stdin_filename, stdout=args.stdout)
     validate_config_output_mode(config)
 
     setup_logging(args.log_level)
diff --git a/src/darker/command_line.py b/src/darker/command_line.py
index 77972663d..fc72274c0 100644
--- a/src/darker/command_line.py
+++ b/src/darker/command_line.py
@@ -9,9 +9,15 @@
 
 import darkgraylib.command_line
 from darker import help as hlp
-from darker.config import DEPRECATED_CONFIG_OPTIONS, DarkerConfig, OutputMode
+from darker.config import (
+    DEPRECATED_CONFIG_OPTIONS,
+    REMOVED_CONFIG_OPTIONS,
+    DarkerConfig,
+    OutputMode,
+)
 from darker.version import __version__
 from darkgraylib.command_line import add_parser_argument
+from darkgraylib.config import ConfigurationError
 
 
 def make_argument_parser(require_src: bool) -> ArgumentParser:
@@ -82,10 +88,17 @@ def make_argument_parser(require_src: bool) -> ArgumentParser:
 
 def show_config_deprecations(config: DarkerConfig) -> None:
     """Show deprecation warnings for configuration keys from the config file."""
+    removal_messages = {
+        REMOVED_CONFIG_OPTIONS[option]
+        for option in config
+        if option in REMOVED_CONFIG_OPTIONS
+    }
+    if removal_messages:
+        raise ConfigurationError(" ".join(sorted(removal_messages)))
     for option in DEPRECATED_CONFIG_OPTIONS & set(config):
         warnings.warn(
             f"The configuration option `{option}` in [tool.darker] is deprecated"
-            " and will be removed in Darker 3.0.",
+            " and will be removed in Darker 4.0.",
             DeprecationWarning,
             stacklevel=2,
         )
@@ -123,5 +136,5 @@ def parse_command_line(
         show_config_deprecations,
     )
     OutputMode.validate_diff_stdout(args.diff, args.stdout)
-    OutputMode.validate_stdout_src(args.stdout, args.src, args.stdin_filename)
+    OutputMode.validate_stdout_src(args.src, args.stdin_filename, stdout=args.stdout)
     return args, effective_cfg, modified_cfg
diff --git a/src/darker/config.py b/src/darker/config.py
index 1324901b0..125d34c3a 100644
--- a/src/darker/config.py
+++ b/src/darker/config.py
@@ -1,16 +1,36 @@
 """Load and save configuration in TOML format"""
 
-from argparse import Namespace
+from __future__ import annotations
+
+import sys
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import Dict, List, Optional, Set, Union
+from typing import TYPE_CHECKING, Dict, List, Union
 
 from darkgraylib.config import BaseConfig, ConfigurationError
 
-UnvalidatedConfig = Dict[str, Union[List[str], str, bool, int]]
+if TYPE_CHECKING:
+    from argparse import Namespace
+
+if sys.version_info < (3, 10):
+    from typing_extensions import TypeAlias
+else:
+    from typing import TypeAlias
+
+UnvalidatedConfig: TypeAlias = Dict[str, Union[List[str], str, bool, int]]
 
 
-DEPRECATED_CONFIG_OPTIONS = {"skip_string_normalization", "skip_magic_trailing_comma"}
+REMOVED_CONFIG_OPTIONS = {
+    "skip_string_normalization": (
+        "Please move the `skip_string_normalization` option from the [tool.darker]"
+        " section to the [tool.black] section in your `pyproject.toml` file."
+    ),
+    "skip_magic_trailing_comma": (
+        "Please move the `skip_magic_trailing_comma` option from the [tool.darker]"
+        " section to the [tool.black] section in your `pyproject.toml` file."
+    ),
+}
+DEPRECATED_CONFIG_OPTIONS: set[str] = set()
 
 
 class DarkerConfig(BaseConfig, total=False):
@@ -19,7 +39,7 @@ class DarkerConfig(BaseConfig, total=False):
     diff: bool
     check: bool
     isort: bool
-    lint: List[str]
+    lint: list[str]
     skip_string_normalization: bool
     skip_magic_trailing_comma: bool
     line_length: int
@@ -53,7 +73,7 @@ def validate_diff_stdout(diff: bool, stdout: bool) -> None:
 
     @staticmethod
     def validate_stdout_src(
-        stdout: bool, src: List[str], stdin_filename: Optional[str]
+        src: list[str], stdin_filename: str | None, *, stdout: bool
     ) -> None:
         """Raise an exception in ``stdout`` mode if not exactly one input is provided"""
         if not stdout:
@@ -92,6 +112,6 @@ class Exclusions:
 
     """
 
-    black: Set[str] = field(default_factory=set)
-    isort: Set[str] = field(default_factory=set)
-    flynt: Set[str] = field(default_factory=set)
+    black: set[str] = field(default_factory=set)
+    isort: set[str] = field(default_factory=set)
+    flynt: set[str] = field(default_factory=set)
diff --git a/src/darker/tests/test_command_line.py b/src/darker/tests/test_command_line.py
index 698a0ba8d..49f9e3f42 100644
--- a/src/darker/tests/test_command_line.py
+++ b/src/darker/tests/test_command_line.py
@@ -262,20 +262,6 @@ def test_parse_command_line(
             " `lint =` option from your configuration file.",
         },
     ),
-    dict(
-        config={"skip_string_normalization": True},
-        expect_warn={
-            "The configuration option `skip_string_normalization` in [tool.darker] is"
-            " deprecated and will be removed in Darker 3.0."
-        },
-    ),
-    dict(
-        config={"skip_magic_trailing_comma": True},
-        expect_warn={
-            "The configuration option `skip_magic_trailing_comma` in [tool.darker] is"
-            " deprecated and will be removed in Darker 3.0."
-        },
-    ),
     dict(config={"line_length": 88}, expect_warn=set()),
     dict(config={"target_version": "py37"}, expect_warn=set()),
     dict(
@@ -285,18 +271,12 @@ def test_parse_command_line(
             "check": True,
             "isort": True,
             "lint": ["dummy"],
-            "skip_string_normalization": True,
-            "skip_magic_trailing_comma": True,
             "line_length": 88,
             "target_version": "py37",
         },
         expect_warn={
             "Baseline linting has been moved to the Graylint package. Please remove the"
             " `lint =` option from your configuration file.",
-            "The configuration option `skip_magic_trailing_comma` in [tool.darker] is"
-            " deprecated and will be removed in Darker 3.0.",
-            "The configuration option `skip_string_normalization` in [tool.darker] is"
-            " deprecated and will be removed in Darker 3.0.",
         },
     ),
 )
@@ -326,6 +306,59 @@ def test_parse_command_line_unknown_conffile_option(tmp_path, monkeypatch):
         parse_command_line(["-"])
 
 
+@pytest.mark.kwparametrize(
+    dict(config={}),
+    dict(config={"diff": True}),
+    dict(config={"stdout": True}),
+    dict(config={"check": True}),
+    dict(config={"isort": True}),
+    dict(config={"lint": ["pylint"]}),
+    dict(
+        config={"skip_string_normalization": True},
+        expect=ConfigurationError(
+            "Please move the `skip_string_normalization` option from the [tool.darker]"
+            " section to the [tool.black] section in your `pyproject.toml` file.",
+        ),
+    ),
+    dict(
+        config={"skip_magic_trailing_comma": True},
+        expect=ConfigurationError(
+            "Please move the `skip_magic_trailing_comma` option from the [tool.darker]"
+            " section to the [tool.black] section in your `pyproject.toml` file.",
+        ),
+    ),
+    dict(config={"line_length": 88}),
+    dict(config={"target_version": "py37"}),
+    dict(
+        config={
+            "diff": True,
+            "stdout": False,
+            "check": True,
+            "isort": True,
+            "lint": ["pylint"],
+            "skip_string_normalization": True,
+            "skip_magic_trailing_comma": True,
+            "line_length": 88,
+            "target_version": "py37",
+        },
+        expect=ConfigurationError(
+            "Please move the `skip_magic_trailing_comma` option from the [tool.darker]"
+            " section to the [tool.black] section in your `pyproject.toml` file. Please"
+            " move the `skip_string_normalization` option from the [tool.darker]"
+            " section to the [tool.black] section in your `pyproject.toml` file.",
+        ),
+    ),
+    expect=None,
+)
+def test_parse_command_line_removed_option(tmp_path, monkeypatch, config, expect):
+    """`parse_command_line` fails if old removed options are used."""
+    monkeypatch.chdir(tmp_path)
+    (tmp_path / "pyproject.toml").write_text(toml.dumps({"tool": {"darker": config}}))
+    with raises_if_exception(expect):
+
+        parse_command_line(["-"])
+
+
 def test_help_description_without_isort_package(capsys):
     """``darker --help`` description shows how to add ``isort`` if it's not present"""
     with isort_present(False):
diff --git a/src/darker/tests/test_config.py b/src/darker/tests/test_config.py
index 1470193ba..62cb7079c 100644
--- a/src/darker/tests/test_config.py
+++ b/src/darker/tests/test_config.py
@@ -107,8 +107,7 @@ def test_output_mode_validate_stdout_src(
     Path("first.py").touch()
     Path("second.py").touch()
     with raises_if_exception(expect):
-
-        OutputMode.validate_stdout_src(stdout, src, stdin_filename)
+        OutputMode.validate_stdout_src(src, stdin_filename, stdout=stdout)
 
 
 @pytest.mark.kwparametrize(