diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index 45c8aa7..cf8ec65 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -398,15 +398,23 @@ public static function preRenderManagedFile($element) {
    * Render API callback: Validates the managed_file element.
    */
   public static function validateManagedFile(&$element, FormStateInterface $form_state, &$complete_form) {
-    // If referencing an existing file, only allow if there are existing
-    // references. This prevents unmanaged files from being deleted if this
-    // item were to be deleted.
     $clicked_button = end($form_state->getTriggeringElement()['#parents']);
     if ($clicked_button != 'remove_button' && !empty($element['fids']['#value'])) {
       $fids = $element['fids']['#value'];
       foreach ($fids as $fid) {
         if ($file = File::load($fid)) {
-          if ($file->isPermanent()) {
+          // If referencing an existing file, only allow if there are existing
+          // references. This prevents unmanaged files from being deleted if
+          // this item were to be deleted. When files that are no longer in use
+          // are automatically marked as temporary (now disabled by default),
+          // it is not safe to reference a permanent file without usage. Adding
+          // removing it again would delete the file, but it is unknown if and
+          // where it is currently referenced. However, when files are not
+          // marked temporary (and then removed) automatically, it is safe to
+          // add and remove usages, as it would simply return to the current
+          // state.
+          // @see https://www.drupal.org/node/2891902
+          if ($file->isPermanent() && \Drupal::config('file.settings')->get('make_unused_managed_files_temporary')) {
             $references = static::fileUsage()->listUsage($file);
             if (empty($references)) {
               // We expect the field name placeholder value to be wrapped in t()
diff --git a/core/modules/file/src/Tests/FileManagedFileElementTest.php b/core/modules/file/src/Tests/FileManagedFileElementTest.php
index 8abff25..1ff00b9 100644
--- a/core/modules/file/src/Tests/FileManagedFileElementTest.php
+++ b/core/modules/file/src/Tests/FileManagedFileElementTest.php
@@ -194,4 +194,55 @@ public function testFileRemovedFromDisk() {
     $file->delete();
   }
 
+  /**
+   * Verify that unused permanent files can be used.
+   */
+  public function testUnusedPermanentFileValidation() {
+
+    // Create a permanent file without usages.
+    $file = $this->getTestFile('image');
+    $file->setPermanent();
+    $file->save();
+
+    // By default, unused files are no longer marked temporary, and it must be
+    // allowed to reference an unused file.
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->drupalPostForm(NULL, [], 'Save');
+    $this->assertNoText('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertText('The file ids are ' . $file->id());
+
+    // Enable marking unused files as tempory, unused permanent files must not
+    // be referenced now.
+    $this->config('file.settings')
+      ->set('make_unused_managed_files_temporary', TRUE)
+      ->save();
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->drupalPostForm(NULL, [], 'Save');
+    $this->assertText('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertNoText('The file ids are ' . $file->id());
+
+    // Make the file temporary, now using it is allowed.
+    $file->setTemporary();
+    $file->save();
+
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->drupalPostForm(NULL, [], 'Save');
+    $this->assertNoText('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertText('The file ids are ' . $file->id());
+
+    // Make the file permanent again and add a usage from itself, referencing is
+    // still allowed.
+    $file->setPermanent();
+    $file->save();
+
+    /** @var \Drupal\file\FileUsage\FileUsageInterface $file_usage */
+    $file_usage = \Drupal::service('file.usage');
+    $file_usage->add($file, 'file', 'file', $file->id());
+
+    $this->drupalGet('file/test/1/0/1/' . $file->id());
+    $this->drupalPostForm(NULL, [], 'Save');
+    $this->assertNoText('The file used in the Managed file & butter field may not be referenced.');
+    $this->assertText('The file ids are ' . $file->id());
+  }
+
 }