Adam G-H
--- a/core/modules/image/tests/src/Kernel/Migrate/d7/MigrateImageSettingsTest.php
+++ b/core/modules/image/tests/src/Kernel/Migrate/d7/MigrateImageSettingsTest.php

  protected static $modules = ['image'];

+  /**
+   * {@inheritdoc}
+   */
+  protected static $configSchemaCheckerExclusions = [
+    // The schema of `image.settings` requires that the `preview_image` value
+    // be a file that actually exists, but that won't be the case in this test.
+    // Therefore, exclude `image.settings` from the schema check; we still
+    // assert that the expected value is migrated.
+    'image.settings',
+  ];
--- a/core/modules/image/config/schema/image.schema.yml
+++ b/core/modules/image/config/schema/image.schema.yml

 image.settings:
  type: config_object
+  constraints:
+    FullyValidatable: ~
  mapping:
    preview_image:
      type: string
      label: 'Preview image'
+      constraints:
+        NotBlank: []
+        # We need to use Symfony's Image constraint because it will accept a file
+        # path as a string, whereas the File module's FileIsImage constraint expects
+        # a full file entity.
+        Image: []
--- a/core/modules/migrate_drupal_ui/tests/src/Functional/d7/Upgrade7Test.php
+++ b/core/modules/migrate_drupal_ui/tests/src/Functional/d7/Upgrade7Test.php
    // Enable saving the logs and set the post migration admin user name.
    $this->outputLogs = TRUE;
    $this->migratedAdminUserName = 'admin';
-    $this->expectedLoggedErrors = 27;
+    $this->expectedLoggedErrors = 29;