diff --git a/.github/workflows/basics.yml b/.github/workflows/basics.yml
index 1631ec74..9102aef8 100644
--- a/.github/workflows/basics.yml
+++ b/.github/workflows/basics.yml
@@ -10,6 +10,12 @@ on:
   # Allow manually triggering the workflow.
   workflow_dispatch:
 
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   checkcs:
     name: 'Basic CS and QA checks'
@@ -37,16 +43,16 @@ jobs:
       - name: 'Composer: adjust dependencies'
         run: |
           # The sniff stage doesn't run the unit tests, so no need for PHPUnit.
-          composer remove --no-update --dev phpunit/phpunit --no-scripts
+          composer remove --no-update --dev phpunit/phpunit --no-scripts --no-interaction
           # Using PHPCS `master` as an early detection system for bugs upstream.
-          composer require --no-update --no-scripts squizlabs/php_codesniffer:"dev-master"
+          composer require --no-update --no-scripts squizlabs/php_codesniffer:"dev-master" --no-interaction
           # Using WPCS `master` (=stable). This can be changed back to `dev-develop` after the WPCS 3.0.0 release.
-          composer require --no-update --no-scripts wp-coding-standards/wpcs:"dev-master"
+          composer require --no-update --no-scripts wp-coding-standards/wpcs:"dev-master" --no-interaction
 
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies
       - name: Install Composer dependencies
-        uses: ramsey/composer-install@v1
+        uses: ramsey/composer-install@v2
 
       - name: Install xmllint
         run: sudo apt-get install --no-install-recommends -y libxml2-utils
diff --git a/.github/workflows/quicktest.yml b/.github/workflows/quicktest.yml
index ca98c0d5..035ebb0f 100644
--- a/.github/workflows/quicktest.yml
+++ b/.github/workflows/quicktest.yml
@@ -10,6 +10,12 @@ on:
   # Allow manually triggering the workflow.
   workflow_dispatch:
 
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   #### QUICK TEST STAGE ####
   # This is a much quicker test which only runs the unit tests and linting against low/high
@@ -24,13 +30,13 @@ jobs:
             phpcs_version: 'dev-master'
             wpcs_version: 'dev-master'
           - php_version: 'latest'
-            phpcs_version: '3.6.0'
+            phpcs_version: '3.6.2'
             wpcs_version: '2.3.0'
           - php_version: '5.4'
             phpcs_version: 'dev-master'
             wpcs_version: '2.3.0'
           - php_version: '5.4'
-            phpcs_version: '3.6.0'
+            phpcs_version: '3.6.2'
             wpcs_version: 'dev-master'
 
     name: "QTest${{ matrix.phpcs_version == 'dev-master' && ' + Lint' || '' }}: PHP ${{ matrix.php_version }} - PHPCS ${{ matrix.phpcs_version }} - WPCS ${{ matrix.wpcs_version }}"
@@ -47,7 +53,7 @@ jobs:
           if [ "${{ matrix.phpcs_version }}" != "dev-master" ]; then
             echo '::set-output name=PHP_INI::error_reporting=E_ALL & ~E_DEPRECATED, display_errors=On'
           else
-            echo '::set-output name=PHP_INI::error_reporting=E_ALL, display_errors=On'
+            echo '::set-output name=PHP_INI::error_reporting=-1, display_errors=On'
           fi
 
       - name: Install PHP
@@ -60,20 +66,20 @@ jobs:
       - name: 'Composer: adjust dependencies'
         run: |
           # Set the PHPCS version to test against.
-          composer require --no-update --no-scripts squizlabs/php_codesniffer:"${{ matrix.phpcs_version }}"
+          composer require --no-update --no-scripts squizlabs/php_codesniffer:"${{ matrix.phpcs_version }}" --no-interaction
           # Set the WPCS version to test against.
-          composer require --no-update --no-scripts wp-coding-standards/wpcs:"${{ matrix.wpcs_version }}"
+          composer require --no-update --no-scripts wp-coding-standards/wpcs:"${{ matrix.wpcs_version }}" --no-interaction
 
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies
       - name: Install Composer dependencies - normal
         if: ${{ startsWith( matrix.php_version, '8' ) == false && matrix.php_version != 'latest' }}
-        uses: ramsey/composer-install@v1
+        uses: ramsey/composer-install@v2
 
       # For the PHP 8.0 and higher, we need to install with ignore platform reqs as not all dependencies allow it.
       - name: Install Composer dependencies - with ignore platform
         if: ${{ startsWith( matrix.php_version, '8' ) || matrix.php_version == 'latest' }}
-        uses: ramsey/composer-install@v1
+        uses: ramsey/composer-install@v2
         with:
           composer-options: --ignore-platform-reqs
 
@@ -84,5 +90,12 @@ jobs:
         if: matrix.phpcs_version == 'dev-master'
         run: composer lint
 
-      - name: Run the unit tests
+      - name: Run the unit tests - PHP 5.4 - 8.0
+        if: ${{ matrix.php_version < '8.1' && matrix.php_version != 'latest' }}
         run: composer test
+
+      - name: Run the unit tests - PHP 8.1+
+        if: ${{ matrix.php_version >= '8.1' || matrix.php_version == 'latest'}}
+        run: composer test -- --no-configuration --dont-report-useless-tests
+        env:
+          PHPCS_IGNORE_TESTS: 'PHPCompatibility,WordPress'
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a57d163b..35cdb925 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -11,6 +11,12 @@ on:
   # Allow manually triggering the workflow.
   workflow_dispatch:
 
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   #### TEST STAGE ####
   test:
@@ -28,8 +34,8 @@ jobs:
         # Note: while WPCS 3.0.0 is under development, the matrix will use `dev-master`.
         # Once it has been released and YoastCS has been made compatible, the matrix should switch (back)
         # WPCS `dev-master` to `dev-develop`.
-        php_version: ['5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
-        phpcs_version: ['3.6.0', 'dev-master']
+        php_version: ['5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1']
+        phpcs_version: ['3.6.2', 'dev-master']
         wpcs_version: ['2.3.0', 'dev-master']
         experimental: [false]
 
@@ -37,7 +43,7 @@ jobs:
           # Experimental builds. These are allowed to fail.
 
           # PHP nightly
-          - php_version: '8.1'
+          - php_version: '8.2'
             phpcs_version: 'dev-master'
             wpcs_version: 'dev-master'
             experimental: true
@@ -69,7 +75,7 @@ jobs:
           if [[ "${{ matrix.phpcs_version }}" != "dev-master" && "${{ matrix.phpcs_version }}" != "4.0.x-dev" ]]; then
             echo '::set-output name=PHP_INI::error_reporting=E_ALL & ~E_DEPRECATED, display_errors=On'
           else
-            echo '::set-output name=PHP_INI::error_reporting=E_ALL, display_errors=On'
+            echo '::set-output name=PHP_INI::error_reporting=-1, display_errors=On'
           fi
 
       - name: Install PHP
@@ -93,25 +99,25 @@ jobs:
       - name: 'Composer: adjust dependencies'
         run: |
           # Set the PHPCS version to test against.
-          composer require --no-update --no-scripts squizlabs/php_codesniffer:"${{ matrix.phpcs_version }}"
+          composer require --no-update --no-scripts squizlabs/php_codesniffer:"${{ matrix.phpcs_version }}" --no-interaction
           # Set the WPCS version to test against.
-          composer require --no-update --no-scripts wp-coding-standards/wpcs:"${{ matrix.wpcs_version }}"
+          composer require --no-update --no-scripts wp-coding-standards/wpcs:"${{ matrix.wpcs_version }}" --no-interaction
 
       - name: 'Composer: conditionally remove PHPCSDevtools'
         if: ${{ startsWith( matrix.phpcs_version, '4' ) }}
         # Remove devtools as it will not (yet) install on PHPCS 4.x.
-        run: composer remove --no-update --dev phpcsstandards/phpcsdevtools
+        run: composer remove --no-update --dev phpcsstandards/phpcsdevtools --no-interaction
 
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies
       - name: Install Composer dependencies - normal
         if: ${{ startsWith( matrix.php_version, '8' ) == false }}
-        uses: ramsey/composer-install@v1
+        uses: ramsey/composer-install@v2
 
       # For the PHP 8/"nightly", we need to install with ignore platform reqs as we're still using PHPUnit 7.
       - name: Install Composer dependencies - with ignore platform
         if: ${{ startsWith( matrix.php_version, '8' ) }}
-        uses: ramsey/composer-install@v1
+        uses: ramsey/composer-install@v2
         with:
           composer-options: --ignore-platform-reqs
 
@@ -125,11 +131,11 @@ jobs:
         run: composer lint -- --checkstyle | cs2pr
 
       - name: Run the unit tests - PHP 5.4 - 8.0
-        if: ${{ matrix.php_version != '8.1' }}
+        if: ${{ matrix.php_version < '8.1' }}
         run: composer test
 
       - name: Run the unit tests - PHP 8.1
-        if: ${{ matrix.php_version == '8.1' }}
+        if: ${{ matrix.php_version >= '8.1' }}
         run: composer test -- --no-configuration --dont-report-useless-tests
         env:
           PHPCS_IGNORE_TESTS: 'PHPCompatibility,WordPress'
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 197e5967..a89d28a0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,17 @@ All notable changes to this project will be documented in this file.
 
 This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a CHANGELOG](https://keepachangelog.com/).
 
+### [2.2.1] - 2022-02-22
+
+#### Changed
+* Composer: Supported version of [PHP_CodeSniffer] has been changed from `^3.6.0` to `^3.6.2`.
+* Composer: Supported version of [PHPCompatibilityWP] has been changed from `^2.1.0` to `^2.1.3`.
+* Composer: Supported version of [PHP Parallel Lint] has been changed from `^1.3.1` to `^1.3.2`.
+* Composer: Supported version of [PHP Console Highlighter] has been changed from `^0.5.0` to `^1.0.0`.
+* Readme: Updated installation instructions for compatibility with Composer 2.2+ and other minor improvements.
+* Various housekeeping.
+
+
 ### [2.2.0] - 2021-09-22
 
 #### Added
@@ -60,7 +71,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 
 #### Changed
 * PHPCS: The default value for the `minimum_supported_wp_version` property which is used by various WPCS sniffs has been updated to WP `5.4` (was `5.3`).
-* Composer: Supported version of the [DealerDirect Composer PHPCS plugin] has been changed to allow for the newly released `0.7.0` version which adds support for Composer 2.0.
+* Composer: Supported version of the [Composer PHPCS plugin] has been changed to allow for the newly released `0.7.0` version which adds support for Composer 2.0.
     Note: this requirement is flexible to prevent conflicts with included standards which may include the plugin as well.
 * Travis: improved testing against the upcoming PHP 8.0.
 * Various housekeeping.
@@ -80,7 +91,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 ### [2.0.1] - 2020-02-06
 
 #### Changed
-* Composer: Supported version of the [DealerDirect Composer PHPCS plugin] has been changed from `^0.5.0` to `^0.5 || ^0.6`.
+* Composer: Supported version of the [Composer PHPCS plugin] has been changed from `^0.5.0` to `^0.5 || ^0.6`.
     Note: this requirement is flexible to prevent conflicts with included standards which may include the plugin as well.
 * Various housekeeping.
 
@@ -136,7 +147,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 * PHPCS: The `PSR12.Files.OpenTag` sniff.
     Enforces that a PHP open tag is on a line by itself in PHP-only files.
 * PHPCS: A `CustomPrefixesTrait` to handle checking names against a list of custom prefixes.
-* Composer: `lint` script which uses the [Parallel-Lint] package for faster and more readable linting results.
+* Composer: `lint` script which uses the [PHP Parallel Lint] package for faster and more readable linting results.
 
 #### Changed
 * :warning: PHPCS: `Yoast.Files.FileName` sniff: the public `$prefixes` property, which can be used to indicate which _prefixes_ should be stripped of a class name when translating it to a file name, has been renamed to `$oo_prefixes`.
@@ -233,7 +244,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 * PHPCS: New `Yoast.Commenting.CodeCoverageIgnoreDeprecated` sniff.
     This sniff verifies that functions which have a `@deprecated` tag in the function docblock, also have a `@codeCoverageIgnore` tag in the same docblock.
 * PHPCS: Added XSD schema tags to the ruleset.
-* Composer: requirement of the [DealerDirect Composer PHPCS plugin] at version `^0.5.0`.
+* Composer: requirement of the [Composer PHPCS plugin] at version `^0.5.0`.
     This means that - in most cases - projects which `require(-dev)` YoastCS, will no longer need to have the plugin in their own `composer.json` and will still get the benefit of it.
 * Travis: Validation of the ruleset against the PHPCS XSD schema.
 * Travis: Testing of the code against PHP 7.3.
@@ -249,7 +260,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 
 #### Removed
 * PHPCS: Minor housekeeping: removed some unused code.
-* Composer: `suggest` section. The [DealerDirect Composer PHPCS plugin] is now included in the `require` section.
+* Composer: `suggest` section. The [Composer PHPCS plugin] is now included in the `require` section.
 
 #### Fixed
 * PHPCS: Various fixes to the `Yoast.Files.TestDoubles` sniff.
@@ -268,7 +279,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 * PHPCS: The `PSR2.Methods.FunctionClosingBrace` sniff to the YoastCS ruleset.
 * PHPCS: The `PSR12.Keywords.ShortFormTypeKeywords` sniff, as introduced in PHP_CodeSniffer 3.3.0, to the YoastCS ruleset.
 * Composer: `roave/security-advisories` dependency to prevent dependencies with known security issues from being installed.
-* Composer: An explanation about the [DealerDirect Composer PHPCS plugin] dependency suggestion this package makes.
+* Composer: An explanation about the [Composer PHPCS plugin] dependency suggestion this package makes.
 * Composer: `--dev` requirement of the [PHPCompatibility] library at version `^8.2.0`.
 
 #### Changed
@@ -305,7 +316,7 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 * PHPCS: An exclusion for the `WordPress.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition` error code.
 * PHPCS: An exclusion for the `WordPress.PHP.StrictInArray.FoundNonStrictFalse` error code.
 * Composer: Repository `type` indicator for compatibility with Composer plugins which handle the setting of the PHP_CodeSniffer `installed_paths` directive.
-* Composer: Suggest requiring the [DealerDirect Composer PHPCS plugin], i.e. `dealerdirect/phpcodesniffer-composer-installer`, for handling the PHP_CodeSniffer `installed_paths` directive at version `^0.4.3`.
+* Composer: Suggest requiring the [Composer PHPCS plugin], i.e. `dealerdirect/phpcodesniffer-composer-installer`, for handling the PHP_CodeSniffer `installed_paths` directive at version `^0.4.3`.
 * Travis: Validation and CS check of the XML files.
 * Travis: Testing of the repo against PHP 7.2.
 * Travis: Checking of the code style of the YoastCS native PHP files.
@@ -434,15 +445,16 @@ This project adheres to [Semantic Versioning](https://semver.org/) and [Keep a C
 Initial public release as a stand-alone package.
 
 
-[PHP_CodeSniffer]: https://github.com/squizlabs/PHP_CodeSniffer/releases
-[WordPressCS]: https://github.com/WordPress/WordPress-Coding-Standards/blob/develop/CHANGELOG.md
-[PHPCompatibilityWP]: https://github.com/PHPCompatibility/PHPCompatibilityWP#changelog
-[PHPCompatibility]: https://github.com/PHPCompatibility/PHPCompatibility/blob/master/CHANGELOG.md
-[PHP Mess Detector]: https://github.com/phpmd/phpmd/blob/master/CHANGELOG
-[DealerDirect Composer PHPCS plugin]: https://github.com/Dealerdirect/phpcodesniffer-composer-installer/releases
-[Parallel-Lint]: https://packagist.org/packages/jakub-onderka/php-parallel-lint
-[PHP Parallel Lint]: https://github.com/php-parallel-lint/PHP-Parallel-Lint/
+[PHP_CodeSniffer]:         https://github.com/squizlabs/PHP_CodeSniffer/releases
+[WordPressCS]:             https://github.com/WordPress/WordPress-Coding-Standards/blob/develop/CHANGELOG.md
+[PHPCompatibilityWP]:      https://github.com/PHPCompatibility/PHPCompatibilityWP#changelog
+[PHPCompatibility]:        https://github.com/PHPCompatibility/PHPCompatibility/blob/master/CHANGELOG.md
+[PHP Mess Detector]:       https://github.com/phpmd/phpmd/blob/master/CHANGELOG
+[Composer PHPCS plugin]:   https://github.com/PHPCSStandards/composer-installer/releases
+[PHP Parallel Lint]:       https://github.com/php-parallel-lint/PHP-Parallel-Lint/releases
+[PHP Console Highlighter]: https://github.com/php-parallel-lint/PHP-Console-Highlighter/releases
 
+[2.2.1]: https://github.com/Yoast/yoastcs/compare/2.2.0...2.2.1
 [2.2.0]: https://github.com/Yoast/yoastcs/compare/2.1.0...2.2.0
 [2.1.0]: https://github.com/Yoast/yoastcs/compare/2.0.2...2.1.0
 [2.0.2]: https://github.com/Yoast/yoastcs/compare/2.0.1...2.0.2
diff --git a/README.md b/README.md
index 295626de..ddba2d04 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,8 @@ Composer will automatically install dependencies, register standards paths, and
 To include standards as part of a project require them as development dependencies:
 
 ```bash
-composer require --dev yoast/yoastcs:^2.0
+composer config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true
+composer require --dev yoast/yoastcs:"^2.0"
 ```
 
 Composer will automatically install dependencies and register the YoastCS and other external standards with PHP_CodeSniffer.
@@ -42,7 +43,7 @@ Typically, (a variation on) the following snippet would be added to the `compose
 ```json
     "scripts" : {
         "lint": [
-            "@php ./vendor/php-parallel-lint/php-parallel-lint/parallel-lint . -e php --exclude vendor --exclude .git"
+            "@php ./vendor/php-parallel-lint/php-parallel-lint/parallel-lint . -e php --show-deprecated --exclude vendor --exclude .git"
         ]
     }
 ```
diff --git a/composer.json b/composer.json
index 6b6febd8..8bc33cad 100644
--- a/composer.json
+++ b/composer.json
@@ -23,12 +23,12 @@
 	},
 	"require": {
 		"php": ">=5.4",
-		"squizlabs/php_codesniffer": "^3.6.0",
+		"squizlabs/php_codesniffer": "^3.6.2",
 		"wp-coding-standards/wpcs": "^2.3.0",
-		"phpcompatibility/phpcompatibility-wp": "^2.1.0",
+		"phpcompatibility/phpcompatibility-wp": "^2.1.3",
 		"dealerdirect/phpcodesniffer-composer-installer": "^0.5 || ^0.6.2 || ^0.7",
-		"php-parallel-lint/php-parallel-lint": "^1.3.1",
-		"php-parallel-lint/php-console-highlighter": "^0.5.0"
+		"php-parallel-lint/php-parallel-lint": "^1.3.2",
+		"php-parallel-lint/php-console-highlighter": "^1.0.0"
 	},
 	"require-dev": {
 		"phpcompatibility/php-compatibility": "^9.3.5",
@@ -36,6 +36,11 @@
 		"phpunit/phpunit": "^4.0 || ^5.0 || ^6.0 || ^7.0",
 		"phpcsstandards/phpcsdevtools": "^1.0"
 	},
+	"config": {
+		"allow-plugins": {
+			"dealerdirect/phpcodesniffer-composer-installer": true
+		}
+	},
 	"minimum-stability": "dev",
 	"prefer-stable": true,
 	"scripts": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index a3416a92..0aa18327 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -5,6 +5,10 @@
 	backupGlobals="true"
 	beStrictAboutTestsThatDoNotTestAnything="false"
 	colors="true"
+	convertErrorsToExceptions="true"
+	convertNoticesToExceptions="true"
+	convertWarningsToExceptions="true"
+	convertDeprecationsToExceptions="true"
 	forceCoversAnnotation="true"
 	>