Issue #2829274 by mr.baileys: Upload-field not migrated if not explicitly enabled on D6

core/modules/file/src/Plugin/migrate/source/d6/UploadInstance.php

@@ -38,13 +38,13 @@ protected function initializeIterator() {
       ->fetchAllKeyed();
     foreach ($node_types as $node_type) {
       $name = 'upload_' . $node_type;
-      if (isset($values[$name])) {
-        $enabled = unserialize($values[$name]);
-        if ($enabled) {
-          $return[$node_type]['node_type'] = $node_type;
-          $return[$node_type]['max_filesize'] = $max_filesize;
-          $return[$node_type]['file_extensions'] = $file_extensions;
-        }
+      // By default, file attachments in D6 are enabled unless upload_<type> is
+      // false, so include types where the upload-variable is not set.
+      $enabled = !isset($values[$name]) || unserialize($values[$name]);
+      if ($enabled) {
+        $return[$node_type]['node_type'] = $node_type;
+        $return[$node_type]['max_filesize'] = $max_filesize;
+        $return[$node_type]['file_extensions'] = $file_extensions;
       }
     }
 

core/modules/migrate_drupal/tests/fixtures/drupal6.php

@@ -45954,8 +45954,32 @@
   'value' => 's:1:"1";',
 ))
 ->values(array(
-  'name' => 'upload_page',
-  'value' => 'b:1;',
+  'name' => 'upload_employee',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_event',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_sponsor',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_test_page',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_test_event',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_test_planet',
+  'value' => 'b:0;',
+))
+->values(array(
+  'name' => 'upload_test_story',
+  'value' => 'b:0;',
 ))
 ->values(array(
   'name' => 'upload_story',