diff -u b/core/modules/migrate/src/Plugin/migrate/process/FileCopy.php b/core/modules/migrate/src/Plugin/migrate/process/FileCopy.php
--- b/core/modules/migrate/src/Plugin/migrate/process/FileCopy.php
+++ b/core/modules/migrate/src/Plugin/migrate/process/FileCopy.php
@@ -94,17 +94,19 @@
     }
 
     $replace = $this->getOverwriteMode();
-    // We attempt the copy first to avoid calling file_prepare_directory() any
-    // more than absolutely necessary.
-    if ($this->writeFile($source, $destination, $replace)) {
-      return $destination;
+    // We attempt the copy or move first to avoid calling file_prepare_directory()
+    // any more than absolutely necessary.
+    $final_destination = $this->writeFile($source, $destination, $replace);
+    if ($final_destination) {
+      return $final_destination;
     }
     $dir = $this->getDirectory($destination);
     if (!file_prepare_directory($dir, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS)) {
       throw new MigrateException("Could not create or write to directory '$dir'");
     }
-    if ($this->writeFile($source, $destination, $replace)) {
-      return $destination;
+    $final_destination = $this->writeFile($source, $destination, $replace);
+    if ($final_destination) {
+      return $final_destination;
     }
     throw new MigrateException("File $source could not be copied to $destination");
   }
@@ -119,15 +121,20 @@
    * @param int $replace
    *   (optional) FILE_EXISTS_REPLACE (default) or FILE_EXISTS_RENAME.
    *
-   * @return bool
-   *   TRUE on success, FALSE on failure.
+   * @return bool|string
+   *   FALSE on failure, destination path on success.
    */
   protected function writeFile($source, $destination, $replace = FILE_EXISTS_REPLACE) {
     if ($this->configuration['move']) {
-      return (boolean) file_unmanaged_move($source, $destination, $replace);
+      if ((boolean) file_unmanaged_move($source, $destination, $replace)) {
+        return $destination;
+      }
     }
-    $destination = file_destination($destination, $replace);
-    return @copy($source, $destination);
+    $final_destination = file_destination($destination, $replace);
+    if (@copy($source, $final_destination)) {
+      return $final_destination;
+    }
+    return FALSE;
   }
 
   /**
diff -u b/core/modules/migrate/tests/src/Unit/process/CopyFileTest.php b/core/modules/migrate/tests/src/Unit/process/CopyFileTest.php
--- b/core/modules/migrate/tests/src/Unit/process/CopyFileTest.php
+++ b/core/modules/migrate/tests/src/Unit/process/CopyFileTest.php
@@ -60,9 +60,10 @@
     ];
     foreach ($data_sets as $data) {
       list($source_path, $destination_path) = $data;
-      $this->doImport($source_path, $destination_path);
-      $message = sprintf('File %s exists', $destination_path);
-      $this->assertTrue(is_file($destination_path), $message);
+      $final_destination = $this->doImport($source_path, $destination_path);
+      $this->assertSame($final_destination, $destination_path);
+      $message = sprintf('File %s exists', $final_destination);
+      $this->assertTrue(is_file($final_destination), $message);
       // Make sure we didn't accidentally do a move.
       $this->assertTrue(is_file($source_path), $message);
     }
@@ -96,9 +97,10 @@
     ];
     foreach ($data_sets as $data) {
       list($source_path, $destination_path) = $data;
-      $this->doImport($source_path, $destination_path, ['move' => TRUE]);
-      $message = sprintf('File %s exists', $destination_path);
-      $this->assertTrue(is_file($destination_path), $message);
+      $final_destination = $this->doImport($source_path, $destination_path, ['move' => TRUE]);
+      $this->assertSame($final_destination, $destination_path);
+      $message = sprintf('File %s exists', $final_destination);
+      $this->assertTrue(is_file($final_destination), $message);
       $message = sprintf('File %s does not exist', $source_path);
       $this->assertTrue(!is_file($source_path), $message);
     }
@@ -123,8 +125,9 @@
     $source = $this->createUri(NULL, NULL, 'temporary');
     $destination = $this->createUri('foo.txt', NULL, 'public');
     $expected_destination = 'public://foo_0.txt';
-    $this->doImport($source, $destination, ['rename' => TRUE]);
-    $this->assertFileExists($expected_destination);
+    $final_destination = $this->doImport($source, $destination, ['rename' => TRUE]);
+    $this->assertSame($expected_destination,$final_destination);
+    $this->assertFileExists($final_destination);
   }
 
   /**
@@ -137,6 +140,9 @@
    * @param array $configuration
    *   Process plugin configuration settings.
    *
+   * @return string $final_destination
+   *   The actual final destination path.
+   *
    * @throws \Drupal\migrate\MigrateException
    */
   protected function doImport($source_path, $destination_path, $configuration = []) {
@@ -144,11 +150,9 @@
     $executable = $this->prophesize(MigrateExecutableInterface::class)->reveal();
     $row = new Row([], []);
 
-    $result = $plugin->transform([$source_path, $destination_path], $executable, $row, 'foobaz');
-
     // The plugin should either throw an exception or return the destination
     // path.
-    $this->assertSame($result, $destination_path);
+    return $plugin->transform([$source_path, $destination_path], $executable, $row, 'foobaz');
   }
 
 }