diff --git a/cms/djangoapps/modulestore_migrator/admin.py b/cms/djangoapps/modulestore_migrator/admin.py
index 8eef778531ac..7da37d18d169 100644
--- a/cms/djangoapps/modulestore_migrator/admin.py
+++ b/cms/djangoapps/modulestore_migrator/admin.py
@@ -178,6 +178,7 @@ class ModulestoreBlockMigrationInline(admin.TabularInline):
         "source",
         "target",
         "change_log_record",
+        "unsupported_reason",
     )
     list_display = ("id", *readonly_fields)
 
diff --git a/cms/djangoapps/modulestore_migrator/api.py b/cms/djangoapps/modulestore_migrator/api.py
index 498d18d8b1fd..317d1cb73db3 100644
--- a/cms/djangoapps/modulestore_migrator/api.py
+++ b/cms/djangoapps/modulestore_migrator/api.py
@@ -1,6 +1,7 @@
 """
 API for migration from modulestore to learning core
 """
+from uuid import UUID
 from collections import defaultdict
 from celery.result import AsyncResult
 from opaque_keys import InvalidKeyError
@@ -181,5 +182,30 @@ def construct_usage_key(lib_key_str: str, component: Component) -> LibraryUsageL
     return {
         obj.source.key: construct_usage_key(obj.target.learning_package.key, obj.target.component)
         for obj in query_set
-        if obj.source.key is not None
+        if obj.source.key is not None and obj.target is not None
     }
+
+
+def get_migration_blocks_info(
+    target_key: str,
+    source_key: str | None,
+    target_collection_key: str | None,
+    task_uuid: str | None,
+    is_failed: bool | None,
+):
+    """
+    Given the target key, and optional source key, target collection key, task_uuid and is_failed get a dictionary
+    containing information about migration blocks.
+    """
+    filters: dict[str, str | UUID | bool] = {
+        'overall_migration__target__key': target_key
+    }
+    if source_key:
+        filters['overall_migration__source__key'] = source_key
+    if target_collection_key:
+        filters['overall_migration__target_collection__key'] = target_collection_key
+    if task_uuid:
+        filters['overall_migration__task_status__uuid'] = UUID(task_uuid)
+    if is_failed is not None:
+        filters['target__isnull'] = is_failed
+    return ModulestoreBlockMigration.objects.filter(**filters)
diff --git a/cms/djangoapps/modulestore_migrator/migrations/0004_alter_modulestoreblockmigration_target_squashed_0005_modulestoreblockmigration_unsupported_reason.py b/cms/djangoapps/modulestore_migrator/migrations/0004_alter_modulestoreblockmigration_target_squashed_0005_modulestoreblockmigration_unsupported_reason.py
new file mode 100644
index 000000000000..f043e208dc35
--- /dev/null
+++ b/cms/djangoapps/modulestore_migrator/migrations/0004_alter_modulestoreblockmigration_target_squashed_0005_modulestoreblockmigration_unsupported_reason.py
@@ -0,0 +1,32 @@
+# Generated by Django 5.2.7 on 2025-11-26 06:35
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('modulestore_migrator', '0003_modulestoremigration_is_failed'),
+        ('oel_publishing', '0008_alter_draftchangelogrecord_options_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='modulestoreblockmigration',
+            name='target',
+            field=models.ForeignKey(
+                blank=True,
+                help_text='The target entity of this block migration, set to null if it fails to migrate',
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                to='oel_publishing.publishableentity',
+            ),
+        ),
+        migrations.AddField(
+            model_name='modulestoreblockmigration',
+            name='unsupported_reason',
+            field=models.TextField(
+                blank=True, help_text='Reason if the block is unsupported and target is set to null', null=True
+            ),
+        ),
+    ]
diff --git a/cms/djangoapps/modulestore_migrator/models.py b/cms/djangoapps/modulestore_migrator/models.py
index 810333fc9be9..149f6dd05d95 100644
--- a/cms/djangoapps/modulestore_migrator/models.py
+++ b/cms/djangoapps/modulestore_migrator/models.py
@@ -6,16 +6,19 @@
 from django.contrib.auth import get_user_model
 from django.db import models
 from django.utils.translation import gettext_lazy as _
-from user_tasks.models import UserTaskStatus
-
 from model_utils.models import TimeStampedModel
 from opaque_keys.edx.django.models import (
     LearningContextKeyField,
     UsageKeyField,
 )
 from openedx_learning.api.authoring_models import (
-    LearningPackage, PublishableEntity, Collection, DraftChangeLog, DraftChangeLogRecord
+    Collection,
+    DraftChangeLog,
+    DraftChangeLogRecord,
+    LearningPackage,
+    PublishableEntity,
 )
+from user_tasks.models import UserTaskStatus
 
 from .data import CompositionLevel, RepeatHandlingStrategy
 
@@ -210,6 +213,9 @@ class ModulestoreBlockMigration(TimeStampedModel):
     target = models.ForeignKey(
         PublishableEntity,
         on_delete=models.CASCADE,
+        help_text=_('The target entity of this block migration, set to null if it fails to migrate'),
+        null=True,
+        blank=True,
     )
     change_log_record = models.OneToOneField(
         DraftChangeLogRecord,
@@ -218,10 +224,16 @@ class ModulestoreBlockMigration(TimeStampedModel):
         null=True,
         on_delete=models.SET_NULL,
     )
+    unsupported_reason = models.TextField(
+        null=True,
+        blank=True,
+        help_text=_('Reason if the block is unsupported and target is set to null'),
+    )
 
     class Meta:
         unique_together = [
             ('overall_migration', 'source'),
+            # By default defining a unique index on a nullable column will only enforce unicity of non-null values.
             ('overall_migration', 'target'),
         ]
 
diff --git a/cms/djangoapps/modulestore_migrator/rest_api/v1/serializers.py b/cms/djangoapps/modulestore_migrator/rest_api/v1/serializers.py
index 8c9f15387647..5aae216a88a8 100644
--- a/cms/djangoapps/modulestore_migrator/rest_api/v1/serializers.py
+++ b/cms/djangoapps/modulestore_migrator/rest_api/v1/serializers.py
@@ -11,7 +11,10 @@
 from user_tasks.serializers import StatusSerializer
 
 from cms.djangoapps.modulestore_migrator.data import CompositionLevel, RepeatHandlingStrategy
-from cms.djangoapps.modulestore_migrator.models import ModulestoreMigration, ModulestoreSource
+from cms.djangoapps.modulestore_migrator.models import (
+    ModulestoreMigration,
+    ModulestoreSource,
+)
 
 
 class ModulestoreMigrationSerializer(serializers.Serializer):
@@ -266,3 +269,12 @@ def get_progress(self, obj: ModulestoreMigration):
         Return the progress of the migration.
         """
         return obj.task_status.completed_steps / obj.task_status.total_steps
+
+
+class BlockMigrationInfoSerializer(serializers.Serializer):
+    """
+    Serializer for the block migration info.
+    """
+    source_key = serializers.CharField(source="source__key")
+    target_key = serializers.CharField(source="target__key")
+    unsupported_reason = serializers.CharField()
diff --git a/cms/djangoapps/modulestore_migrator/rest_api/v1/urls.py b/cms/djangoapps/modulestore_migrator/rest_api/v1/urls.py
index 44c872c6657a..208825e0c01a 100644
--- a/cms/djangoapps/modulestore_migrator/rest_api/v1/urls.py
+++ b/cms/djangoapps/modulestore_migrator/rest_api/v1/urls.py
@@ -1,9 +1,16 @@
 """
 Course to Library Import API v1 URLs.
 """
-from django.urls import path, include
+from django.urls import include, path
 from rest_framework.routers import SimpleRouter
-from .views import MigrationViewSet, BulkMigrationViewSet, MigrationInfoViewSet, LibraryCourseMigrationViewSet
+
+from .views import (
+    BlockMigrationInfo,
+    BulkMigrationViewSet,
+    LibraryCourseMigrationViewSet,
+    MigrationInfoViewSet,
+    MigrationViewSet,
+)
 
 ROUTER = SimpleRouter()
 ROUTER.register(r'migrations', MigrationViewSet, basename='migrations')
@@ -17,4 +24,5 @@
 urlpatterns = [
     path('', include(ROUTER.urls)),
     path('migration_info/', MigrationInfoViewSet.as_view(), name='migration-info'),
+    path('migration_blocks/', BlockMigrationInfo.as_view(), name='migration-blocks'),
 ]
diff --git a/cms/djangoapps/modulestore_migrator/rest_api/v1/views.py b/cms/djangoapps/modulestore_migrator/rest_api/v1/views.py
index 3d887fff15f7..7ad377d7a3b7 100644
--- a/cms/djangoapps/modulestore_migrator/rest_api/v1/views.py
+++ b/cms/djangoapps/modulestore_migrator/rest_api/v1/views.py
@@ -7,33 +7,37 @@
 from edx_rest_framework_extensions.auth.jwt.authentication import JwtAuthentication
 from edx_rest_framework_extensions.auth.session.authentication import SessionAuthenticationAllowInactiveUser
 from opaque_keys import InvalidKeyError
+from opaque_keys.edx.keys import CourseKey
 from opaque_keys.edx.locator import LibraryLocatorV2
 from rest_framework import status
 from rest_framework.exceptions import ParseError
+from rest_framework.fields import BooleanField
 from rest_framework.mixins import ListModelMixin
 from rest_framework.permissions import IsAdminUser, IsAuthenticated
+from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.views import APIView
 from rest_framework.viewsets import GenericViewSet
 from user_tasks.models import UserTaskStatus
 from user_tasks.views import StatusViewSet
-from opaque_keys.edx.keys import CourseKey
 
 from cms.djangoapps.modulestore_migrator.api import (
-    start_migration_to_library,
-    start_bulk_migration_to_library,
     get_all_migrations_info,
+    get_migration_blocks_info,
+    start_bulk_migration_to_library,
+    start_migration_to_library,
 )
+from common.djangoapps.student.auth import has_studio_write_access
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangoapps.content_libraries import api as lib_api
 from openedx.core.lib.api.authentication import BearerAuthenticationAllowInactiveUser
-from common.djangoapps.student.auth import has_studio_write_access
 
 from ...models import ModulestoreMigration
 from .serializers import (
+    BlockMigrationInfoSerializer,
     BulkModulestoreMigrationSerializer,
-    MigrationInfoResponseSerializer,
     LibraryMigrationCourseSerializer,
+    MigrationInfoResponseSerializer,
     ModulestoreMigrationSerializer,
     StatusWithModulestoreMigrationsSerializer,
 )
@@ -493,3 +497,105 @@ def get_queryset(self):
         queryset = queryset.filter(target__key=library_key, source__key__startswith='course-v1')
 
         return queryset
+
+
+class BlockMigrationInfo(APIView):
+    """
+    Retrieve migration blocks information given task_uuid, source_key or target_key.
+
+    It returns the migration block information for each block migrated by a specific task.
+
+    API Endpoints
+    -------------
+    GET /api/modulestore_migrator/v1/migration_blocks/
+        Retrieve migration blocks info for given task_uuid, source_key or target_key.
+
+        Query parameters:
+            task_uuid (str): task uuid
+                Example: ?task_uuid=dfe72eca-c54f-4b43-b53b-7996031f2102
+            source_key (str): Source content key
+                Example: ?source_key=course-v1:UNIX+UX1+2025_T3
+            target_key (str): target content key
+                Example: ?target_key=lib:UNIX:CIT1
+            is_failed (boolean): has the block failed to migrate/import
+                Example: ?is_failed=true
+
+        Example request:
+            GET /api/modulestore_migrator/v1/migration_blocks/?task_uuid=dfe72eca-c54f-4b43-b53b&is_failed=true
+
+        Example response:
+    """
+
+    permission_classes = (IsAuthenticated,)
+    authentication_classes = (
+        BearerAuthenticationAllowInactiveUser,
+        JwtAuthentication,
+        SessionAuthenticationAllowInactiveUser,
+    )
+
+    @apidocs.schema(
+        parameters=[
+            apidocs.string_parameter(
+                "target_key",
+                apidocs.ParameterLocation.QUERY,
+                description="Filter blocks by target key",
+            ),
+            apidocs.string_parameter(
+                "source_key",
+                apidocs.ParameterLocation.QUERY,
+                description="Filter blocks by source key",
+            ),
+            apidocs.string_parameter(
+                "target_collection_key",
+                apidocs.ParameterLocation.QUERY,
+                description="Filter blocks by target_collection_key",
+            ),
+            apidocs.string_parameter(
+                "task_uuid",
+                apidocs.ParameterLocation.QUERY,
+                description="Filter blocks by task_uuid",
+            ),
+            apidocs.string_parameter(
+                "is_failed",
+                apidocs.ParameterLocation.QUERY,
+                description="Filter blocks based on its migration status",
+            ),
+        ],
+        responses={
+            200: MigrationInfoResponseSerializer,
+            400: "Missing required parameter: target_key",
+            401: "The requester is not authenticated.",
+        },
+    )
+    def get(self, request: Request):
+        """
+        Handle the migration info `GET` request
+        """
+        source_key = request.query_params.get("source_key")
+        target_key = request.query_params.get("target_key")
+        target_collection_key = request.query_params.get("target_collection_key")
+        task_uuid = request.query_params.get("task_uuid")
+        is_failed: str | bool | None = request.query_params.get("is_failed")
+        if not target_key:
+            return Response({"error": "Target key cannot be blank."}, status=400)
+        try:
+            target_key_parsed = LibraryLocatorV2.from_string(target_key)
+        except InvalidKeyError as e:
+            return Response({"error": str(e)}, status=400)
+        lib_api.require_permission_for_library_key(
+            target_key_parsed,
+            request.user,
+            lib_api.permissions.CAN_VIEW_THIS_CONTENT_LIBRARY
+        )
+        if is_failed is not None:
+            is_failed = BooleanField().to_internal_value(is_failed)
+
+        data = get_migration_blocks_info(
+            target_key,
+            source_key,
+            target_collection_key,
+            task_uuid,
+            is_failed,
+        ).values('source__key', 'target__key', 'unsupported_reason')
+        serializer = BlockMigrationInfoSerializer(data, many=True)
+        return Response(serializer.data)
diff --git a/cms/djangoapps/modulestore_migrator/tasks.py b/cms/djangoapps/modulestore_migrator/tasks.py
index ef2386c69d34..b4f24f149b8e 100644
--- a/cms/djangoapps/modulestore_migrator/tasks.py
+++ b/cms/djangoapps/modulestore_migrator/tasks.py
@@ -9,13 +9,15 @@
 from dataclasses import dataclass
 from datetime import datetime, timezone
 from enum import Enum
+from gettext import ngettext
 from itertools import groupby
 
 from celery import shared_task
 from celery.utils.log import get_task_logger
 from django.core.exceptions import ObjectDoesNotExist
-from django.utils.text import slugify
 from django.db import transaction
+from django.utils.text import slugify
+from django.utils.translation import gettext_lazy as _
 from edx_django_utils.monitoring import set_code_owner_attribute_from_module
 from lxml import etree
 from lxml.etree import _ElementTree as XmlTree
@@ -26,7 +28,7 @@
     LibraryContainerLocator,
     LibraryLocator,
     LibraryLocatorV2,
-    LibraryUsageLocatorV2
+    LibraryUsageLocatorV2,
 )
 from openedx_learning.api import authoring as authoring_api
 from openedx_learning.api.authoring_models import (
@@ -35,14 +37,13 @@
     ComponentType,
     LearningPackage,
     PublishableEntity,
-    PublishableEntityVersion
+    PublishableEntityVersion,
 )
 from user_tasks.tasks import UserTask, UserTaskStatus
 from xblock.core import XBlock
-from django.utils.translation import gettext_lazy as _
 
 from common.djangoapps.split_modulestore_django.models import SplitModulestoreCourseIndex
-from common.djangoapps.util.date_utils import strftime_localized, DEFAULT_DATE_TIME_FORMAT
+from common.djangoapps.util.date_utils import DEFAULT_DATE_TIME_FORMAT, strftime_localized
 from openedx.core.djangoapps.content_libraries import api as libraries_api
 from openedx.core.djangoapps.content_libraries.api import ContainerType, get_library
 from openedx.core.djangoapps.content_staging import api as staging_api
@@ -84,7 +85,7 @@ class _MigrationTask(UserTask):
     """
 
     @staticmethod
-    def calculate_total_steps(arguments_dict):
+    def calculate_total_steps(arguments_dict):  # pylint: disable=unused-argument
         """
         Get number of in-progress steps in importing process, as shown in the UI.
         """
@@ -126,7 +127,7 @@ class _MigrationContext:
     Context for the migration process.
     """
     existing_source_to_target_keys: dict[  # Note: It's intended to be mutable to reflect changes during migration.
-        UsageKey, list[PublishableEntity]
+        UsageKey, list[PublishableEntity | None]
     ]
     target_package_id: int
     target_library_key: LibraryLocatorV2
@@ -141,7 +142,7 @@ class _MigrationContext:
     def is_already_migrated(self, source_key: UsageKey) -> bool:
         return source_key in self.existing_source_to_target_keys
 
-    def get_existing_target(self, source_key: UsageKey) -> PublishableEntity:
+    def get_existing_target(self, source_key: UsageKey) -> PublishableEntity | None:
         """
         Get the target entity for a given source key.
 
@@ -154,7 +155,13 @@ def get_existing_target(self, source_key: UsageKey) -> PublishableEntity:
         # NOTE: This is a list of PublishableEntities, but we always return the first one.
         return self.existing_source_to_target_keys[source_key][0]
 
-    def add_migration(self, source_key: UsageKey, target: PublishableEntity) -> None:
+    def is_already_successfully_migrated(self, source_key: UsageKey) -> bool:
+        """
+        Check whether a source has successfully been migrated. This means it exists and has at least one target.
+        """
+        return self.is_already_migrated(source_key) and self.get_existing_target(source_key) is not None
+
+    def add_migration(self, source_key: UsageKey, target: PublishableEntity | None) -> None:
         """Update the context with a new migration (keeps it current)"""
         if source_key not in self.existing_source_to_target_keys:
             self.existing_source_to_target_keys[source_key] = [target]
@@ -166,7 +173,7 @@ def get_existing_target_entity_keys(self, base_key: str) -> set[str]:
             publishable_entity.key
             for publishable_entity_list in self.existing_source_to_target_keys.values()
             for publishable_entity in publishable_entity_list
-            if publishable_entity.key.startswith(base_key)
+            if publishable_entity and publishable_entity.key.startswith(base_key)
         )
 
     @property
@@ -372,7 +379,7 @@ def _import_structure(
     # a given LearningPackage.
     # We use this mapping to ensure that we don't create duplicate
     # PublishableEntities during the migration process for a given LearningPackage.
-    existing_source_to_target_keys: dict[UsageKey, list[PublishableEntity]] = {}
+    existing_source_to_target_keys: dict[UsageKey, list[PublishableEntity | None]] = {}
     modulestore_blocks = (
         ModulestoreBlockMigration.objects.filter(overall_migration__target=migration.target.id).order_by("source__key")
     )
@@ -450,7 +457,7 @@ def _create_collection(library_key: LibraryLocatorV2, title: str) -> Collection:
     The same is true for the title.
     """
     key = slugify(title)
-    collection = None
+    collection: Collection | None = None
     attempt = 0
     created_at = strftime_localized(datetime.now(timezone.utc), DEFAULT_DATE_TIME_FORMAT)
     description = f"{_('This collection contains content migrated from a legacy library on')}: {created_at}"
@@ -465,7 +472,7 @@ def _create_collection(library_key: LibraryLocatorV2, title: str) -> Collection:
                     title=f"{title}{f'_{attempt}' if attempt > 0 else ''}",
                     description=description,
                 )
-        except libraries_api.LibraryCollectionAlreadyExists as e:
+        except libraries_api.LibraryCollectionAlreadyExists:
             attempt += 1
     return collection
 
@@ -925,6 +932,9 @@ def bulk_migrate_from_modulestore(
         status.fail(str(exc))
 
 
+SourceToTarget = tuple[UsageKey, PublishableEntityVersion | None, str | None]
+
+
 @dataclass(frozen=True)
 class _MigratedNode:
     """
@@ -934,10 +944,10 @@ class _MigratedNode:
     This happens, particularly, if the node is above the requested composition level
     but has descendents which are at or below that level.
     """
-    source_to_target: tuple[UsageKey, PublishableEntityVersion] | None
+    source_to_target: SourceToTarget | None
     children: list[_MigratedNode]
 
-    def all_source_to_target_pairs(self) -> t.Iterable[tuple[UsageKey, PublishableEntityVersion]]:
+    def all_source_to_target_pairs(self) -> t.Iterable[SourceToTarget]:
         """
         Get all source_key->target_ver pairs via a pre-order traversal.
         """
@@ -995,13 +1005,13 @@ def _migrate_node(
             )
             for source_node_child in source_node.getchildren()
         ]
-    source_to_target: tuple[UsageKey, PublishableEntityVersion] | None = None
+    source_to_target: SourceToTarget | None = None
     if should_migrate_node:
         source_olx = etree.tostring(source_node).decode('utf-8')
         if source_block_id := source_node.get('url_name'):
             source_key: UsageKey = context.source_context_key.make_usage_key(source_node.tag, source_block_id)
             title = source_node.get('display_name', source_block_id)
-            target_entity_version = (
+            target_entity_version, reason = (
                 _migrate_container(
                     context=context,
                     source_key=source_key,
@@ -1010,7 +1020,7 @@ def _migrate_node(
                     children=[
                         migrated_child.source_to_target[1]
                         for migrated_child in migrated_children if
-                        migrated_child.source_to_target
+                        migrated_child.source_to_target and migrated_child.source_to_target[1]
                     ],
                 )
                 if container_type else
@@ -1021,9 +1031,19 @@ def _migrate_node(
                     title=title,
                 )
             )
-            if target_entity_version:
-                source_to_target = (source_key, target_entity_version)
-                context.add_migration(source_key, target_entity_version.entity)
+            if container_type is None and target_entity_version is None and reason is not None:
+                # Currently, components with children are not supported
+                children_length = len(source_node.getchildren())
+                if children_length:
+                    reason += (
+                        ngettext(
+                            ' It has {count} children block.',
+                            ' It has {count} children blocks.',
+                            children_length,
+                        )
+                    ).format(count=children_length)
+            source_to_target = (source_key, target_entity_version, reason)
+            context.add_migration(source_key, target_entity_version.entity if target_entity_version else None)
         else:
             log.warning(
                 f"Cannot migrate node from {context.source_context_key} to {context.target_library_key} "
@@ -1039,12 +1059,14 @@ def _migrate_container(
     container_type: ContainerType,
     title: str,
     children: list[PublishableEntityVersion],
-) -> PublishableEntityVersion:
+) -> tuple[PublishableEntityVersion, str | None]:
     """
     Create, update, or replace a container in a library based on a source key and children.
 
     (We assume that the destination is a library rather than some other future kind of learning
-     package, but let's keep than an internal assumption.)
+    package, but let's keep than an internal assumption.)
+    For now this returns None value for unsupported_reason as second value of tuple as we
+    don't have any concrete condition where a container cannot be imported/migrated.
     """
     target_key = _get_distinct_target_container_key(
         context,
@@ -1076,7 +1098,7 @@ def _migrate_container(
         return PublishableEntityVersion.objects.get(
             entity_id=container.container_pk,
             version_num=container.draft_version_num,
-        )
+        ), None
 
     container_publishable_entity_version = authoring_api.create_next_container_version(
         container.container_pk,
@@ -1099,7 +1121,7 @@ def _migrate_container(
         context.created_by,
         call_post_publish_events_sync=True,
     )
-    return container_publishable_entity_version
+    return container_publishable_entity_version, None
 
 
 def _migrate_component(
@@ -1108,7 +1130,7 @@ def _migrate_component(
     source_key: UsageKey,
     olx: str,
     title: str,
-) -> PublishableEntityVersion | None:
+) -> tuple[PublishableEntityVersion | None, str | None]:
     """
     Create, update, or replace a component in a library based on a source key and OLX.
 
@@ -1141,7 +1163,7 @@ def _migrate_component(
             )
         except libraries_api.IncompatibleTypesError as e:
             log.error(f"Error validating block for library {context.target_library_key}: {e}")
-            return None
+            return None, str(e)
         component = authoring_api.create_component(
             context.target_package_id,
             component_type=component_type,
@@ -1152,7 +1174,7 @@ def _migrate_component(
 
     # Component existed and we do not replace it and it is not deleted previously
     if component_existed and not component_deleted and context.should_skip_strategy:
-        return component.versioning.draft.publishable_entity_version
+        return component.versioning.draft.publishable_entity_version, None
 
     # If component existed and was deleted or we have to replace the current version
     # Create the new component version for it
@@ -1171,7 +1193,7 @@ def _migrate_component(
         libraries_api.library_component_usage_key(context.target_library_key, component),
         context.created_by,
     )
-    return component_version.publishable_entity_version
+    return component_version.publishable_entity_version, None
 
 
 def _get_distinct_target_container_key(
@@ -1194,8 +1216,10 @@ def _get_distinct_target_container_key(
     """
     # Check if we already processed this block and we are not forking. If we are forking, we will
     # want a new target key.
-    if context.is_already_migrated(source_key) and not context.should_fork_strategy:
+    if context.is_already_successfully_migrated(source_key) and not context.should_fork_strategy:
         existing_version = context.get_existing_target(source_key)
+        # This is not possible, just to satisfy type checker.
+        assert existing_version is not None
 
         return LibraryContainerLocator(
             context.target_library_key,
@@ -1240,9 +1264,11 @@ def _get_distinct_target_usage_key(
     """
     # Check if we already processed this block and we are not forking. If we are forking, we will
     # want a new target key.
-    if context.is_already_migrated(source_key) and not context.should_fork_strategy:
+    if context.is_already_successfully_migrated(source_key) and not context.should_fork_strategy:
         log.debug(f"Block {source_key} already exists, reusing first existing target")
         existing_target = context.get_existing_target(source_key)
+        # This is not possible, just to satisfy type checker.
+        assert existing_target is not None
         block_id = existing_target.component.local_key
 
         # mypy thinks LibraryUsageLocatorV2 is abstract. It's not.
@@ -1325,7 +1351,7 @@ def _create_migration_artifacts_incrementally(
     total_nodes = len(nodes)
     processed = 0
 
-    for source_usage_key, target_version in root_migrated_node.all_source_to_target_pairs():
+    for source_usage_key, target_version, reason in root_migrated_node.all_source_to_target_pairs():
         block_source, _ = ModulestoreBlockSource.objects.get_or_create(
             overall_source=source,
             key=source_usage_key
@@ -1334,7 +1360,8 @@ def _create_migration_artifacts_incrementally(
         ModulestoreBlockMigration.objects.create(
             overall_migration=migration,
             source=block_source,
-            target_id=target_version.entity_id,
+            target_id=target_version.entity_id if target_version else None,
+            unsupported_reason=reason,
         )
 
         processed += 1
diff --git a/cms/djangoapps/modulestore_migrator/tests/test_tasks.py b/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
index 244d435de50a..9b4ac4130c59 100644
--- a/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
+++ b/cms/djangoapps/modulestore_migrator/tests/test_tasks.py
@@ -3,38 +3,39 @@
 """
 
 from unittest.mock import Mock, patch
+
 import ddt
 from django.utils import timezone
 from lxml import etree
 from opaque_keys.edx.keys import CourseKey
 from opaque_keys.edx.locator import LibraryLocator, LibraryLocatorV2
-from openedx_learning.api.authoring_models import Collection, PublishableEntityVersion
 from openedx_learning.api import authoring as authoring_api
+from openedx_learning.api.authoring_models import Collection, PublishableEntityVersion
 from organizations.tests.factories import OrganizationFactory
 from user_tasks.models import UserTaskArtifact
 from user_tasks.tasks import UserTaskStatus
-from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
-from xmodule.modulestore.tests.factories import CourseFactory, LibraryFactory
 
-from common.djangoapps.student.tests.factories import UserFactory
 from cms.djangoapps.modulestore_migrator.data import CompositionLevel, RepeatHandlingStrategy
 from cms.djangoapps.modulestore_migrator.models import (
     ModulestoreMigration,
     ModulestoreSource,
 )
 from cms.djangoapps.modulestore_migrator.tasks import (
+    MigrationStep,
+    _BulkMigrationTask,
     _migrate_component,
     _migrate_container,
     _migrate_node,
     _MigratedNode,
     _MigrationContext,
     _MigrationTask,
-    _BulkMigrationTask,
-    migrate_from_modulestore,
     bulk_migrate_from_modulestore,
-    MigrationStep,
+    migrate_from_modulestore,
 )
+from common.djangoapps.student.tests.factories import UserFactory
 from openedx.core.djangoapps.content_libraries import api as lib_api
+from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
+from xmodule.modulestore.tests.factories import CourseFactory, LibraryFactory
 
 
 @ddt.ddt
@@ -235,9 +236,10 @@ def test_migrate_node_container_composition_level(
 
         if should_migrate:
             self.assertIsNotNone(result.source_to_target)
-            source_key, _ = result.source_to_target
+            source_key, _, reason = result.source_to_target
             self.assertEqual(source_key.block_type, tag_name)
             self.assertEqual(source_key.block_id, f"test_{tag_name}")
+            self.assertIsNone(reason)
         else:
             self.assertIsNone(result.source_to_target)
 
@@ -269,6 +271,45 @@ def test_migrate_node_without_url_name(self):
         self.assertIsNone(result.source_to_target)
         self.assertEqual(len(result.children), 0)
 
+    def test_migrate_node_with_children_components(self):
+        """
+        Test _migrate_node handles nodes with children components
+        """
+        node_without_url_name = etree.fromstring('''
+        <library_content display_name="Test lib content" url_name="test_library_content">
+        <problem display_name="Test Problem"><multiplechoiceresponse></multiplechoiceresponse></problem>
+        <problem display_name="Test Problem2"><multiplechoiceresponse></multiplechoiceresponse></problem>
+        </library_content>
+        ''')
+        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_node(
+            context=context,
+            source_node=node_without_url_name,
+        )
+
+        self.assertEqual(
+            result.source_to_target,
+            (
+                self.course.id.make_usage_key('library_content', 'test_library_content'),
+                None,
+                'The "library_content" XBlock (ID: "test_library_content") has children, '
+                'so it not supported in content libraries. It has 2 children blocks.',
+            ),
+        )
+        self.assertEqual(len(result.children), 0)
+
     def test_migrated_node_all_source_to_target_pairs(self):
         """
         Test _MigratedNode.all_source_to_target_pairs traversal
@@ -281,11 +322,11 @@ def test_migrated_node_all_source_to_target_pairs(self):
         key2 = self.course.id.make_usage_key("problem", "problem2")
         key3 = self.course.id.make_usage_key("problem", "problem3")
 
-        child_node = _MigratedNode(source_to_target=(key3, mock_version3), children=[])
+        child_node = _MigratedNode(source_to_target=(key3, mock_version3, None), children=[])
         parent_node = _MigratedNode(
-            source_to_target=(key1, mock_version1),
+            source_to_target=(key1, mock_version1, None),
             children=[
-                _MigratedNode(source_to_target=(key2, mock_version2), children=[]),
+                _MigratedNode(source_to_target=(key2, mock_version2, None), children=[]),
                 child_node,
             ],
         )
@@ -426,13 +467,14 @@ def test_migrate_component_success(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_component(
+        result, reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
             title="test_problem"
         )
 
+        self.assertIsNone(reason)
         self.assertIsNotNone(result)
         self.assertIsInstance(result, PublishableEntityVersion)
 
@@ -443,6 +485,44 @@ def test_migrate_component_success(self):
         # The component is published
         self.assertFalse(result.componentversion.component.versioning.has_unpublished_changes)
 
+    def test_migrate_component_failure(self):
+        """
+        Test _migrate_component fails to import component with children
+        """
+        source_key = self.course.id.make_usage_key("library_content", "test_library_content")
+        olx = '''
+        <library_content display_name="Test lib content">
+        <problem display_name="Test Problem"><multiplechoiceresponse></multiplechoiceresponse></problem>
+        <problem display_name="Test Problem2"><multiplechoiceresponse></multiplechoiceresponse></problem>
+        </library_content>
+        '''
+        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, reason = _migrate_component(
+            context=context,
+            source_key=source_key,
+            olx=olx,
+            title="test_library content"
+        )
+
+        self.assertIsNone(result)
+        self.assertEqual(
+            reason,
+            'The "library_content" XBlock (ID: "test_library_content") has children,'
+            ' so it not supported in content libraries.',
+        )
+
     def test_migrate_component_with_static_content(self):
         """
         Test _migrate_component with static file content
@@ -470,7 +550,7 @@ def test_migrate_component_with_static_content(self):
             created_at=timezone.now(),
             created_by=self.user.id,
         )
-        result = _migrate_component(
+        result, reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
@@ -478,6 +558,7 @@ def test_migrate_component_with_static_content(self):
         )
 
         self.assertIsNotNone(result)
+        self.assertIsNone(reason)
 
         component_content = result.componentversion.componentversioncontent_set.filter(
             key="static/test_image.png"
@@ -504,7 +585,7 @@ def test_migrate_component_replace_existing_false(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_component(
+        first_result, first_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
@@ -513,12 +594,14 @@ def test_migrate_component_replace_existing_false(self):
 
         context.existing_source_to_target_keys[source_key] = [first_result.entity]
 
-        second_result = _migrate_component(
+        second_result, second_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx='<problem display_name="Updated Problem"><multiplechoiceresponse></multiplechoiceresponse></problem>',
             title="updated_problem"
         )
+        self.assertIsNone(first_reason)
+        self.assertIsNone(second_reason)
 
         self.assertEqual(first_result.entity_id, second_result.entity_id)
         self.assertEqual(first_result.version_num, second_result.version_num)
@@ -546,7 +629,7 @@ def test_migrate_component_same_title(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_component(
+        first_result, first_reason = _migrate_component(
             context=context,
             source_key=source_key_1,
             olx=olx,
@@ -555,12 +638,14 @@ def test_migrate_component_same_title(self):
 
         context.existing_source_to_target_keys[source_key_1] = [first_result.entity]
 
-        second_result = _migrate_component(
+        second_result, second_reason = _migrate_component(
             context=context,
             source_key=source_key_2,
             olx=olx,
             title="test_problem"
         )
+        self.assertIsNone(first_reason)
+        self.assertIsNone(second_reason)
 
         self.assertNotEqual(first_result.entity_id, second_result.entity_id)
         self.assertNotEqual(first_result.entity.key, second_result.entity.key)
@@ -584,7 +669,7 @@ def test_migrate_component_replace_existing_true(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_component(
+        first_result, first_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=original_olx,
@@ -594,12 +679,14 @@ def test_migrate_component_replace_existing_true(self):
         context.existing_source_to_target_keys[source_key] = [first_result.entity]
 
         updated_olx = '<problem display_name="Updated"><multiplechoiceresponse></multiplechoiceresponse></problem>'
-        second_result = _migrate_component(
+        second_result, second_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=updated_olx,
             title="updated"
         )
+        self.assertIsNone(first_reason)
+        self.assertIsNone(second_reason)
 
         self.assertEqual(first_result.entity_id, second_result.entity_id)
         self.assertNotEqual(first_result.version_num, second_result.version_num)
@@ -626,7 +713,7 @@ def test_migrate_component_different_block_types(self):
                 created_by=self.user.id,
             )
 
-            result = _migrate_component(
+            result, reason = _migrate_component(
                 context=context,
                 source_key=source_key,
                 olx=olx,
@@ -634,6 +721,7 @@ def test_migrate_component_different_block_types(self):
             )
 
             self.assertIsNotNone(result, f"Failed to migrate {block_type}")
+            self.assertIsNone(reason)
 
             self.assertEqual(
                 block_type, result.componentversion.component.component_type.name
@@ -679,7 +767,7 @@ def test_migrate_component_content_filename_not_in_olx(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_component(
+        result, reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
@@ -687,6 +775,7 @@ def test_migrate_component_content_filename_not_in_olx(self):
         )
 
         self.assertIsNotNone(result)
+        self.assertIsNone(reason)
 
         referenced_content_exists = (
             result.componentversion.componentversioncontent_set.filter(
@@ -722,7 +811,7 @@ def test_migrate_component_library_source_key(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_component(
+        result, reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
@@ -730,6 +819,7 @@ def test_migrate_component_library_source_key(self):
         )
 
         self.assertIsNotNone(result)
+        self.assertIsNone(reason)
 
         self.assertEqual(
             "problem", result.componentversion.component.component_type.name
@@ -765,21 +855,23 @@ def test_migrate_component_duplicate_content_integrity_error(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_component(
+        first_result, first_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
             title="test_problem"
         )
+        self.assertIsNone(first_reason)
 
         context.existing_source_to_target_keys[source_key] = [first_result.entity]
 
-        second_result = _migrate_component(
+        second_result, second_reason = _migrate_component(
             context=context,
             source_key=source_key,
             olx=olx,
             title="test_problem"
         )
+        self.assertIsNone(second_reason)
 
         self.assertIsNotNone(first_result)
         self.assertIsNotNone(second_result)
@@ -840,7 +932,7 @@ def test_migrate_container_creates_new_container(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_container(
+        result, reason = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -848,6 +940,7 @@ def test_migrate_container_creates_new_container(self):
             children=children,
         )
 
+        self.assertIsNone(reason)
         self.assertIsInstance(result, PublishableEntityVersion)
 
         container_version = result.containerversion
@@ -888,7 +981,7 @@ def test_migrate_container_different_container_types(self):
                     block_type, f"test_{block_type}"
                 )
 
-                result = _migrate_container(
+                result, reason = _migrate_container(
                     context=context,
                     source_key=source_key,
                     container_type=container_type,
@@ -896,6 +989,7 @@ def test_migrate_container_different_container_types(self):
                     children=[],
                 )
 
+                self.assertIsNone(reason)
                 self.assertIsNotNone(result)
 
                 container_version = result.containerversion
@@ -921,7 +1015,7 @@ def test_migrate_container_replace_existing_false(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_container(
+        first_result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -931,7 +1025,7 @@ def test_migrate_container_replace_existing_false(self):
 
         context.existing_source_to_target_keys[source_key] = [first_result.entity]
 
-        second_result = _migrate_container(
+        second_result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -967,7 +1061,7 @@ def test_migrate_container_same_title(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_container(
+        first_result, _ = _migrate_container(
             context=context,
             source_key=source_key_1,
             container_type=lib_api.ContainerType.Unit,
@@ -977,7 +1071,7 @@ def test_migrate_container_same_title(self):
 
         context.existing_source_to_target_keys[source_key_1] = [first_result.entity]
 
-        second_result = _migrate_container(
+        second_result, _ = _migrate_container(
             context=context,
             source_key=source_key_2,
             container_type=lib_api.ContainerType.Unit,
@@ -1027,7 +1121,7 @@ def test_migrate_container_replace_existing_true(self):
             created_by=self.user.id,
         )
 
-        first_result = _migrate_container(
+        first_result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1037,7 +1131,7 @@ def test_migrate_container_replace_existing_true(self):
 
         context.existing_source_to_target_keys[source_key] = [first_result.entity]
 
-        second_result = _migrate_container(
+        second_result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1071,7 +1165,7 @@ def test_migrate_container_with_library_source_key(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_container(
+        result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1102,7 +1196,7 @@ def test_migrate_container_empty_children_list(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_container(
+        result, reason = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1110,6 +1204,7 @@ def test_migrate_container_empty_children_list(self):
             children=[],
         )
 
+        self.assertIsNone(reason)
         self.assertIsNotNone(result)
 
         container_version = result.containerversion
@@ -1151,7 +1246,7 @@ def test_migrate_container_preserves_child_order(self):
             )
             children.append(child_version.publishable_entity_version)
 
-        result = _migrate_container(
+        result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1240,7 +1335,7 @@ def test_migrate_container_with_mixed_child_types(self):
             created_by=self.user.id,
         )
 
-        result = _migrate_container(
+        result, _ = _migrate_container(
             context=context,
             source_key=source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1279,7 +1374,7 @@ def test_migrate_container_generates_correct_target_key(self):
             created_by=self.user.id,
         )
 
-        course_result = _migrate_container(
+        course_result, _ = _migrate_container(
             context=context,
             source_key=course_source_key,
             container_type=lib_api.ContainerType.Unit,
@@ -1291,7 +1386,7 @@ def test_migrate_container_generates_correct_target_key(self):
         library_key = LibraryLocator(org="TestOrg", library="TestLibrary")
         library_source_key = library_key.make_usage_key("vertical", "test_vertical")
 
-        library_result = _migrate_container(
+        library_result, _ = _migrate_container(
             context=context,
             source_key=library_source_key,
             container_type=lib_api.ContainerType.Unit,
diff --git a/openedx/core/djangoapps/content_libraries/api/blocks.py b/openedx/core/djangoapps/content_libraries/api/blocks.py
index be5b296147fd..4cf46627d1d2 100644
--- a/openedx/core/djangoapps/content_libraries/api/blocks.py
+++ b/openedx/core/djangoapps/content_libraries/api/blocks.py
@@ -298,7 +298,7 @@ def validate_can_add_block_to_library(
     component_count = authoring_api.get_all_drafts(content_library.learning_package_id).count()
     if component_count + 1 > settings.MAX_BLOCKS_PER_CONTENT_LIBRARY:
         raise BlockLimitReachedError(
-            _("Library cannot have more than {} Components").format(
+            _("Library cannot have more than {} Components.").format(
                 settings.MAX_BLOCKS_PER_CONTENT_LIBRARY
             )
         )
@@ -309,7 +309,9 @@ def validate_can_add_block_to_library(
     block_class = XBlock.load_class(block_type)  # Will raise an exception if invalid
     if block_class.has_children:
         raise IncompatibleTypesError(
-            'The "{block_type}" XBlock (ID: "{block_id}") has children, so it not supported in content libraries',
+            _(
+                'The "{block_type}" XBlock (ID: "{block_id}") has children, so it not supported in content libraries.'
+            ).format(block_type=block_type, block_id=block_id)
         )
     # Make sure the new ID is not taken already:
     usage_key = LibraryUsageLocatorV2(  # type: ignore[abstract]
@@ -319,7 +321,9 @@ def validate_can_add_block_to_library(
     )
 
     if _component_exists(usage_key):
-        raise LibraryBlockAlreadyExists(f"An XBlock with ID '{usage_key}' already exists")
+        raise LibraryBlockAlreadyExists(
+            _("An XBlock with ID '{usage_key}' already exists.").format(usage_key=usage_key)
+        )
 
     return content_library, usage_key
 
diff --git a/openedx/core/lib/xblock_serializer/block_serializer.py b/openedx/core/lib/xblock_serializer/block_serializer.py
index 76611624cdc6..169352730e1c 100644
--- a/openedx/core/lib/xblock_serializer/block_serializer.py
+++ b/openedx/core/lib/xblock_serializer/block_serializer.py
@@ -79,10 +79,15 @@ def _serialize_block(self, block) -> etree.Element:
         else:
             olx = self._serialize_normal_block(block)
 
-        # The url_name attribute can come either because it was already in the
-        # block's field data, or because this class adds it in the calls above.
-        # However it gets set though, we can remove it here:
-        if not self.write_url_name:
+        if self.write_url_name:
+            # Handles a weird case where url_name is not part of olx.attrib even if it is
+            # set in block. Known case is with openassessment blocks.
+            if "url_name" not in olx.attrib and hasattr(block, "url_name"):
+                olx.attrib['url_name'] = block.url_name
+        else:
+            # The url_name attribute can come either because it was already in the
+            # block's field data, or because this class adds it in the calls above.
+            # However it gets set though, we can remove it here:
             olx.attrib.pop("url_name", None)
 
         # Add copied_from_block and copied_from_version attribute the XBlock's OLX node, to help identify the source of