diff --git a/core/includes/schema.inc b/core/includes/schema.inc
index 87cbfa4085..8863a24b48 100644
--- a/core/includes/schema.inc
+++ b/core/includes/schema.inc
@@ -5,7 +5,7 @@
  * Schema API handling functions.
  */
 
-use Drupal\Core\Utility\SchemaTypecaster;
+use Drupal\Component\Utility\SchemaTypecaster;
 use Drupal\Core\Schema\SchemaDataInterface;
 
 /**
@@ -16,7 +16,7 @@
 /**
  * Indicates that a module has not been installed yet.
  *
- * @deprecated in Drupal 8.7.0, will be removed before Drupal 9.0.0.
+ * @deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0.
  *   Use \Drupal\Core\Schema\SchemaDataInterface::UNINSTALLED instead.
  *
  * @see https://www.drupal.org/node/2444417
@@ -33,13 +33,13 @@
  *   If the module has updates, an array of available updates sorted by
  *   version. Otherwise, FALSE.
  *
- * @deprecated in Drupal 8.7.0, will be removed before Drupal 9.0.0.
+ * @deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0.
  *   Use \Drupal\Core\Schema\SchemaDataInterface::getVersions() instead.
  *
  * @see https://www.drupal.org/node/2444417
  */
 function drupal_get_schema_versions($module) {
-  @trigger_error('drupal_get_schema_versions() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Schema\SchemaDataInterface::getVersions() instead. See https://www.drupal.org/node/2444417.', E_USER_DEPRECATED);
+  @trigger_error('drupal_get_schema_versions() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Schema\SchemaDataInterface::getVersions() instead. See https://www.drupal.org/node/2444417', E_USER_DEPRECATED);
   $versions = \Drupal::service('schema.data')->getVersions($module);
   // Service returns an empty array instead of FALSE as before.
   return $versions ?: FALSE;
@@ -57,8 +57,9 @@ function drupal_get_schema_versions($module) {
  *   system.
  *
  * @return string|int
- *   The currently installed schema version, or SCHEMA_UNINSTALLED if the
- *   module is not installed.
+ *   The currently installed schema version, or
+ *   \Drupal\Core\Schema\SchemaDataInterface::UNINSTALLED if the module is not
+ *   installed.
  */
 function drupal_get_installed_schema_version($module, $reset = FALSE, $array = FALSE) {
   $versions = &drupal_static(__FUNCTION__, []);
@@ -77,7 +78,7 @@ function drupal_get_installed_schema_version($module, $reset = FALSE, $array = F
     return $versions;
   }
   else {
-    return isset($versions[$module]) ? $versions[$module] : SCHEMA_UNINSTALLED;
+    return isset($versions[$module]) ? $versions[$module] : SchemaDataInterface::UNINSTALLED;
   }
 }
 
@@ -203,13 +204,13 @@ function _drupal_schema_initialize(&$schema, $module, $remove_descriptions = TRU
  * @return mixed
  *   The converted value.
  *
- * @deprecated in Drupal 8.7.0, will be removed before Drupal 9.0.0.
- *   Drupal\Core\Utility\SchemaTypecaster::castValue() instead.
+ * @deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0.
+ *   Use \Drupal\Component\Utility\SchemaTypecaster::castValue() instead.
  *
  * @eee https://www.drupal.org/node/2444417
  */
 function drupal_schema_get_field_value(array $info, $value) {
-  @trigger_error('drupal_schema_get_field_value() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Core\Schema\SchemaData::getFieldValue($info, $value) instead. See https://www.drupal.org/node/2444417.', E_USER_DEPRECATED);
+  @trigger_error('drupal_schema_get_field_value() is deprecated in Drupal 8.7.0 and will be removed before Drupal 9.0.0. Use \Drupal\Component\Utility\SchemaTypecaster::castValue($info, $value) instead. See https://www.drupal.org/node/2444417', E_USER_DEPRECATED);
   return SchemaTypecaster::castValue($info, $value);
 }
 
diff --git a/core/includes/update.inc b/core/includes/update.inc
index 85ca44385d..e7258b57a9 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -9,6 +9,7 @@
  */
 
 use Drupal\Component\Graph\Graph;
+use Drupal\Core\Schema\SchemaDataInterface;
 use Drupal\Core\Update\UpdateKernel;
 use Drupal\Core\Utility\Error;
 
@@ -307,9 +308,10 @@ function update_get_update_list() {
   $ret = ['system' => []];
 
   $modules = drupal_get_installed_schema_version(NULL, FALSE, TRUE);
+  $schema_data = \Drupal::service('schema.data');
   foreach ($modules as $module => $schema_version) {
     // Skip uninstalled and incompatible modules.
-    if ($schema_version == SCHEMA_UNINSTALLED || update_check_incompatibility($module)) {
+    if ($schema_version == SchemaDataInterface::UNINSTALLED || update_check_incompatibility($module)) {
       continue;
     }
     // Display a requirements error if the user somehow has a schema version
@@ -319,7 +321,7 @@ function update_get_update_list() {
       continue;
     }
     // Otherwise, get the list of updates defined by this module.
-    $updates = \Drupal::service('schema.data')->getVersions($module);
+    $updates = $schema_data->getVersions($module);
     if ($updates) {
       // \Drupal::moduleHandler()->invoke() returns NULL for non-existing hooks,
       // so if no updates are removed, it will == 0.
@@ -454,9 +456,10 @@ function update_get_update_function_list($starting_updates) {
   // Go through each module and find all updates that we need (including the
   // first update that was requested and any updates that run after it).
   $update_functions = [];
+  $schema_data = \Drupal::service('schema.data');
   foreach ($starting_updates as $module => $version) {
     $update_functions[$module] = [];
-    $updates = \Drupal::service('schema.data')->getVersions($module);
+    $updates = $schema_data->getVersions($module);
     if ($updates) {
       $max_version = max($updates);
       if ($version <= $max_version) {
@@ -609,7 +612,7 @@ function update_retrieve_dependencies() {
   // Get a list of installed modules, arranged so that we invoke their hooks in
   // the same order that \Drupal::moduleHandler()->invokeAll() does.
   foreach (\Drupal::keyValue('system.schema')->getAll() as $module => $schema) {
-    if ($schema == SCHEMA_UNINSTALLED) {
+    if ($schema == SchemaDataInterface::UNINSTALLED) {
       // Nothing to upgrade.
       continue;
     }
diff --git a/core/lib/Drupal/Component/Utility/SchemaTypecaster.php b/core/lib/Drupal/Component/Utility/SchemaTypecaster.php
index d0518a2ee2..c570ab99a8 100644
--- a/core/lib/Drupal/Component/Utility/SchemaTypecaster.php
+++ b/core/lib/Drupal/Component/Utility/SchemaTypecaster.php
@@ -24,7 +24,7 @@ class SchemaTypecaster {
    * @return mixed
    *   The converted value.
    *
-   * @see Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema
+   * @see \Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema
    */
   public static function castValue(array $info, $value) {
     // Preserve legal NULL values.
diff --git a/core/lib/Drupal/Core/Extension/ModuleExtensionList.php b/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
index c8f492bd4f..798d752952 100644
--- a/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
+++ b/core/lib/Drupal/Core/Extension/ModuleExtensionList.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Schema\SchemaDataInterface;
 use Drupal\Core\State\StateInterface;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 
@@ -173,7 +174,7 @@ protected function doList() {
     foreach ($extensions as $name => $module) {
       $module->weight = isset($installed_modules[$name]) ? $installed_modules[$name] : 0;
       $module->status = (int) isset($installed_modules[$name]);
-      $module->schema_version = SCHEMA_UNINSTALLED;
+      $module->schema_version = SchemaDataInterface::UNINSTALLED;
     }
     $extensions = $this->moduleHandler->buildModuleDependencies($extensions);
 
diff --git a/core/lib/Drupal/Core/Extension/ModuleInstaller.php b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
index 86dd86eeda..3545aa9163 100644
--- a/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -77,13 +77,11 @@ public function __construct($root, ModuleHandlerInterface $module_handler, Drupa
     $this->root = $root;
     $this->moduleHandler = $module_handler;
     $this->kernel = $kernel;
-    if ($schema) {
-      $this->schema = $schema;
-    }
-    else {
+    if (!$schema) {
       @trigger_error('\Drupal\Core\Schema\SchemaDataInterface became an optional dependency of this class in Drupal 8.7.0 and will be required before Drupal 9.0.0. See https://www.drupal.org/project/drupal/issues/2124069.', E_USER_DEPRECATED);
-      $this->schema = \Drupal::service('schema.data');
+      $schema = \Drupal::service('schema.data');
     }
+    $this->schema = $schema;
   }
 
   /**
diff --git a/core/modules/system/src/Form/ModulesUninstallForm.php b/core/modules/system/src/Form/ModulesUninstallForm.php
index 841a741e44..2e924fc415 100644
--- a/core/modules/system/src/Form/ModulesUninstallForm.php
+++ b/core/modules/system/src/Form/ModulesUninstallForm.php
@@ -7,6 +7,7 @@
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\KeyValueStore\KeyValueStoreExpirableInterface;
+use Drupal\Core\Schema\SchemaDataInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -142,7 +143,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       // All modules which depend on this one must be uninstalled first, before
       // we can allow this module to be uninstalled.
       foreach (array_keys($module->required_by) as $dependent) {
-        if (drupal_get_installed_schema_version($dependent) != SCHEMA_UNINSTALLED) {
+        if (drupal_get_installed_schema_version($dependent) != SchemaDataInterface::UNINSTALLED) {
           $name = isset($modules[$dependent]->info['name']) ? $modules[$dependent]->info['name'] : $dependent;
           $form['modules'][$module->getName()]['#required_by'][] = $name;
           $form['uninstall'][$module->getName()]['#disabled'] = TRUE;
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 7d04188cf9..4e116e3f43 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -723,8 +723,9 @@ function system_requirements($phase) {
 
     // Check installed modules.
     $has_pending_updates = FALSE;
+    $schema_data = \Drupal::service('schema.data');
     foreach (\Drupal::moduleHandler()->getModuleList() as $module => $filename) {
-      $updates = \Drupal::service('schema.data')->getVersions($module);
+      $updates = $schema_data->getVersions($module);
       if ($updates) {
         $default = drupal_get_installed_schema_version($module);
         if (max($updates) > $default) {
@@ -745,7 +746,7 @@ function system_requirements($phase) {
     if ($has_pending_updates) {
       $requirements['update']['severity'] = REQUIREMENT_ERROR;
       $requirements['update']['value'] = t('Out of date');
-      $requirements['update']['description'] = t('Some modules have database schema updates to install. You should run the <a href=":update">database update script</a> immediately.', [':update' => \Drupal::url('system.db_update')]);
+      $requirements['update']['description'] = t('Some modules have database schema_data updates to install. You should run the <a href=":update">database update script</a> immediately.', [':update' => \Drupal::url('system.db_update')]);
     }
 
     $requirements['entity_update'] = [
diff --git a/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php b/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
index 976032e050..eecd60ad0d 100644
--- a/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
+++ b/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Extension\MissingDependencyException;
 use Drupal\Core\Extension\ModuleUninstallValidatorException;
+use Drupal\Core\Schema\SchemaDataInterface;
 use Drupal\entity_test\Entity\EntityTest;
 use Drupal\KernelTests\KernelTestBase;
 
@@ -126,7 +127,7 @@ public function testDependencyResolution() {
     $this->assertTrue($result, 'ModuleInstaller::uninstall() returned TRUE.');
 
     foreach (['color', 'config', 'help'] as $module) {
-      $this->assertEqual(drupal_get_installed_schema_version($module), SCHEMA_UNINSTALLED, "$module module was uninstalled.");
+      $this->assertEqual(drupal_get_installed_schema_version($module), SchemaDataInterface::UNINSTALLED, "$module module was uninstalled.");
     }
     $uninstalled_modules = \Drupal::state()->get('module_test.uninstall_order') ?: [];
     $this->assertEqual($uninstalled_modules, ['color', 'config', 'help'], 'Modules were uninstalled in the correct order.');
@@ -182,7 +183,7 @@ public function testUninstallProfileDependencyBC() {
     $result = $this->moduleInstaller()->uninstall([$dependency]);
     $this->assertTrue($result, 'ModuleInstaller::uninstall() returns TRUE.');
     $this->assertFalse($this->moduleHandler()->moduleExists($dependency));
-    $this->assertEqual(drupal_get_installed_schema_version($dependency), SCHEMA_UNINSTALLED, "$dependency module was uninstalled.");
+    $this->assertEqual(drupal_get_installed_schema_version($dependency), SchemaDataInterface::UNINSTALLED, "$dependency module was uninstalled.");
 
     // Verify that the installation profile itself was not uninstalled.
     $uninstalled_modules = \Drupal::state()->get('module_test.uninstall_order') ?: [];
@@ -217,7 +218,7 @@ public function testUninstallProfileDependency() {
     $result = $this->moduleInstaller()->uninstall([$non_dependency]);
     $this->assertTrue($result, 'ModuleInstaller::uninstall() returns TRUE.');
     $this->assertFalse($this->moduleHandler()->moduleExists($non_dependency));
-    $this->assertEquals(drupal_get_installed_schema_version($non_dependency), SCHEMA_UNINSTALLED, "$non_dependency module was uninstalled.");
+    $this->assertEquals(drupal_get_installed_schema_version($non_dependency), SchemaDataInterface::UNINSTALLED, "$non_dependency module was uninstalled.");
 
     // Verify that the installation profile itself was not uninstalled.
     $uninstalled_modules = \Drupal::state()->get('module_test.uninstall_order') ?: [];
@@ -311,7 +312,7 @@ public function testUninstallContentDependency() {
 
     $result = $this->moduleInstaller()->uninstall(['help']);
     $this->assertTrue($result, 'ModuleInstaller::uninstall() returns TRUE.');
-    $this->assertEqual(drupal_get_installed_schema_version('entity_test'), SCHEMA_UNINSTALLED, "entity_test module was uninstalled.");
+    $this->assertEqual(drupal_get_installed_schema_version('entity_test'), SchemaDataInterface::UNINSTALLED, "entity_test module was uninstalled.");
   }
 
   /**