diff --git a/api/app/core/error_codes.py b/api/app/core/error_codes.py
index 3feae4f6..41f58734 100644
--- a/api/app/core/error_codes.py
+++ b/api/app/core/error_codes.py
@@ -19,6 +19,7 @@ class BizCode(IntEnum):
     TENANT_NOT_FOUND = 3002
     WORKSPACE_NO_ACCESS = 3003
     WORKSPACE_INVITE_NOT_FOUND = 3004
+    WORKSPACE_ACCESS_DENIED = 3005
     # API Key 管理（3xxx）
     API_KEY_NOT_FOUND = 3007
     API_KEY_DUPLICATE_NAME = 3008
@@ -113,6 +114,8 @@ HTTP_MAPPING = {
     BizCode.FORBIDDEN: 403,
     BizCode.TENANT_NOT_FOUND: 400,
     BizCode.WORKSPACE_NO_ACCESS: 403,
+    BizCode.WORKSPACE_INVITE_NOT_FOUND: 400,
+    BizCode.WORKSPACE_ACCESS_DENIED: 403,
     BizCode.NOT_FOUND: 400,
     BizCode.USER_NOT_FOUND: 200,
     BizCode.WORKSPACE_NOT_FOUND: 400,
diff --git a/api/app/core/workflow/adapters/dify/converter.py b/api/app/core/workflow/adapters/dify/converter.py
index f0cb32dd..41459d8d 100644
--- a/api/app/core/workflow/adapters/dify/converter.py
+++ b/api/app/core/workflow/adapters/dify/converter.py
@@ -496,7 +496,23 @@ class DifyConverter(BaseConverter):
     def convert_assigner_node_config(self, node: dict) -> dict:
         node_data = node["data"]
         assignments = []
-        for assignment in node_data["items"]:
+
+        # Support both formats:
+        # 1. New format: node_data["items"] list
+        # 2. Flat format: assigned_variable_selector + input_variable_selector + write_mode
+        if "items" in node_data:
+            raw_items = node_data["items"]
+        elif "assigned_variable_selector" in node_data and "input_variable_selector" in node_data:
+            raw_items = [{
+                "variable_selector": node_data["assigned_variable_selector"],
+                "value": node_data["input_variable_selector"],
+                "input_type": ValueInputType.VARIABLE,
+                "operation": node_data.get("write_mode", "over-write"),
+            }]
+        else:
+            raw_items = []
+
+        for assignment in raw_items:
             if assignment.get("operation") is None or assignment.get("value") is None:
                 continue
             assignments.append(
diff --git a/api/app/core/workflow/nodes/list_operator/config.py b/api/app/core/workflow/nodes/list_operator/config.py
index c178ec59..6fde6a57 100644
--- a/api/app/core/workflow/nodes/list_operator/config.py
+++ b/api/app/core/workflow/nodes/list_operator/config.py
@@ -1,5 +1,5 @@
 from typing import Any
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
 
 from app.core.workflow.nodes.base_config import BaseNodeConfig
 from app.core.workflow.nodes.enums import ComparisonOperator
@@ -31,6 +31,11 @@ class ExtractConfig(BaseModel):
     enabled: bool = False
     serial: str = "1"  # 1-based index string, e.g. "1" = first
 
+    @field_validator("serial", mode="before")
+    @classmethod
+    def coerce_serial(cls, v):
+        return str(v)
+
 
 class ListOperatorNodeConfig(BaseNodeConfig):
     """
diff --git a/api/app/core/workflow/utils/file_processor.py b/api/app/core/workflow/utils/file_processor.py
index 9b07d2e9..0bedf9a7 100644
--- a/api/app/core/workflow/utils/file_processor.py
+++ b/api/app/core/workflow/utils/file_processor.py
@@ -91,7 +91,7 @@ async def fetch_remote_file_meta(
     """
     import httpx
 
-    name = size = mime_type = extension = None
+    name = extension = None
     try:
         async with httpx.AsyncClient(timeout=10.0) as client:
             resp = await client.head(url, follow_redirects=True)
diff --git a/api/app/services/workflow_service.py b/api/app/services/workflow_service.py
index 5fccee54..b771c639 100644
--- a/api/app/services/workflow_service.py
+++ b/api/app/services/workflow_service.py
@@ -25,7 +25,7 @@ from app.repositories.workflow_repository import (
     WorkflowExecutionRepository,
     WorkflowNodeExecutionRepository
 )
-from app.schemas import DraftRunRequest, FileInput
+from app.schemas import DraftRunRequest, FileInput, FileType
 from app.services.conversation_service import ConversationService
 from app.services.multi_agent_service import convert_uuids_to_str
 from app.services.multimodal_service import MultimodalService
@@ -466,7 +466,7 @@ class WorkflowService:
             if not isinstance(item, dict) or item.get("is_file"):
                 return item
             transfer_method = item.get("transfer_method", "remote_url")
-            file_type = item.get("type", "document")
+            file_type = FileType.trans(item.get("type", "document"))
             origin_file_type = item.get("file_type") or file_type
             if transfer_method == "remote_url":
                 url = item.get("url", "")