From a2ef5151012bb76f773e501a7116ac263d0289e7 Mon Sep 17 00:00:00 2001
From: Navin Karkera <navin@opencraft.com>
Date: Fri, 12 Dec 2025 22:17:02 +0530
Subject: [PATCH] fix: handle PluginMissingError while migrating legacy blocks
 to libraries v2 (#37732)

Unhandled exception while migration legacy xblocks into new library stops the migration process abruptly causing following issues:

* Components not being collected into Collections for successful migrations
* Data being corrupted for already migrated blocks most likely due to incomplete transaction.

(cherry picked from commit a3cc78a37726cc9e49497d2eed8b99b16927ef14)
---
 cms/djangoapps/modulestore_migrator/tasks.py  |  4 +++
 .../modulestore_migrator/tests/test_tasks.py  | 28 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/cms/djangoapps/modulestore_migrator/tasks.py b/cms/djangoapps/modulestore_migrator/tasks.py
index ef2386c69d34..fd2fa5a4fd07 100644
--- a/cms/djangoapps/modulestore_migrator/tasks.py
+++ b/cms/djangoapps/modulestore_migrator/tasks.py
@@ -40,6 +40,7 @@
 from user_tasks.tasks import UserTask, UserTaskStatus
 from xblock.core import XBlock
 from django.utils.translation import gettext_lazy as _
+from xblock.plugin import PluginMissingError
 
 from common.djangoapps.split_modulestore_django.models import SplitModulestoreCourseIndex
 from common.djangoapps.util.date_utils import strftime_localized, DEFAULT_DATE_TIME_FORMAT
@@ -1142,6 +1143,9 @@ def _migrate_component(
         except libraries_api.IncompatibleTypesError as e:
             log.error(f"Error validating block for library {context.target_library_key}: {e}")
             return None
+        except PluginMissingError as e:
+            log.error(f"Block type not supported in {context.target_library_key}: {e}")
+            return None
         component = authoring_api.create_component(
             context.target_package_id,
             component_type=component_type,
diff --git a/cms/djangoapps/modulestore_migrator/tests/test_tasks.py b/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
index 244d435de50a..4335d615ad2f 100644
--- a/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
+++ b/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
@@ -1748,6 +1748,34 @@ def test_bulk_migrate_invalid_source_key_type(self):
             f"Not a valid source context key: {invalid_key}. Source key must reference a course or a legacy library."
         )
 
+    def test_migrate_component_with_fake_block_type(self):
+        """
+        Test _migrate_component with with_fake_block_type
+        """
+        source_key = self.course.id.make_usage_key("fake_block", "test_fake_block")
+        olx = '<fake_block display_name="Test fake_block"></fake_block>'
+        context = _MigrationContext(
+            existing_source_to_target_keys={},
+            target_package_id=self.learning_package.id,
+            target_library_key=self.library.library_key,
+            source_context_key=self.course.id,
+            content_by_filename={},
+            composition_level=CompositionLevel.Unit,
+            repeat_handling_strategy=RepeatHandlingStrategy.Skip,
+            preserve_url_slugs=True,
+            created_at=timezone.now(),
+            created_by=self.user.id,
+        )
+
+        result = _migrate_component(
+            context=context,
+            source_key=source_key,
+            olx=olx,
+            title="test"
+        )
+
+        self.assertIsNone(result)
+
     def test_migrate_from_modulestore_nonexistent_modulestore_item(self):
         """
         Test migration when modulestore item doesn't exist