Issue #3517070 by bbrala: Remove system.file.path config from system.schema.yml

core/modules/system/config/schema/system.schema.yml

@@ -344,6 +344,7 @@ system.file:
     path:
       type: mapping
       label: 'Path settings'
+      deprecated: "The 'path' config schema is deprecated in drupal:11.2.0 and will be removed from drupal 12.0.0. Use 'file_temp_path' key in settings.php instead. See https://www.drupal.org/node/3039255."
     temporary_maximum_age:
       type: integer
       label: 'Maximum age for temporary files'

core/modules/system/system.post_update.php

@@ -92,3 +92,14 @@ function system_post_update_sdc_uninstall(): void {
 function system_post_update_remove_rss_cdata_subscriber(): void {
   // Empty update to trigger container rebuild.
 }
+
+/**
+ * Remove path key in system.file.
+ */
+function system_post_update_remove_path_key(): void {
+  if (\Drupal::config('system.file')->get('path') !== NULL) {
+    \Drupal::configFactory()->getEditable('system.file')
+      ->clear('path')
+      ->save();
+  }
+}

core/modules/system/tests/src/Functional/Update/RemovePathKeyTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\system\Functional\Update;
+
+use Drupal\FunctionalTests\Update\UpdatePathTestBase;
+
+/**
+ * Tests the upgrade path for the system.file schema update.
+ *
+ * @group Update
+ */
+class RemovePathKeyTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setDatabaseDumpFiles(): void {
+    $this->databaseDumpFiles = [
+      __DIR__ . '/../../../../../system/tests/fixtures/update/drupal-10.3.0.bare.standard.php.gz',
+    ];
+  }
+
+  /**
+   * Tests the upgrade path for removing system.file.path key.
+   */
+  public function testRunUpdates(): void {
+    $this->assertIsArray(\Drupal::config('system.file')->get('path'));
+    $this->runUpdates();
+    $this->assertNull(\Drupal::config('system.file')->get('path'));
+  }
+
+}