diff --git a/api/core/app/apps/advanced_chat/app_runner.py b/api/core/app/apps/advanced_chat/app_runner.py
index d7764e9543..b8eeb0e986 100644
--- a/api/core/app/apps/advanced_chat/app_runner.py
+++ b/api/core/app/apps/advanced_chat/app_runner.py
@@ -28,7 +28,7 @@ from core.workflow.enums import WorkflowType
 from core.workflow.graph_engine.command_channels.redis_channel import RedisChannel
 from core.workflow.graph_engine.layers.base import GraphEngineLayer
 from core.workflow.graph_engine.layers.persistence import PersistenceWorkflowInfo, WorkflowPersistenceLayer
-from core.workflow.nodes.variable_assigner.common.impl import conversation_variable_updater_factory
+from services.conversation_variable_updater import conversation_variable_updater_factory
 from core.workflow.repositories.workflow_execution_repository import WorkflowExecutionRepository
 from core.workflow.repositories.workflow_node_execution_repository import WorkflowNodeExecutionRepository
 from core.workflow.runtime import GraphRuntimeState, VariablePool
diff --git a/api/services/conversation_service.py b/api/services/conversation_service.py
index 659e7406fb..8ee09b4db7 100644
--- a/api/services/conversation_service.py
+++ b/api/services/conversation_service.py
@@ -11,7 +11,7 @@ from core.app.entities.app_invoke_entities import InvokeFrom
 from core.db.session_factory import session_factory
 from core.llm_generator.llm_generator import LLMGenerator
 from core.variables.types import SegmentType
-from core.workflow.nodes.variable_assigner.common.impl import conversation_variable_updater_factory
+from services.conversation_variable_updater import conversation_variable_updater_factory
 from extensions.ext_database import db
 from factories import variable_factory
 from libs.datetime_utils import naive_utc_now
diff --git a/api/core/workflow/nodes/variable_assigner/common/impl.py b/api/services/conversation_variable_updater.py
similarity index 85%
rename from api/core/workflow/nodes/variable_assigner/common/impl.py
rename to api/services/conversation_variable_updater.py
index 050e213535..91dfa4fef3 100644
--- a/api/core/workflow/nodes/variable_assigner/common/impl.py
+++ b/api/services/conversation_variable_updater.py
@@ -5,8 +5,6 @@ from core.variables.variables import Variable
 from extensions.ext_database import db
 from models import ConversationVariable
 
-from .exc import VariableOperatorNodeError
-
 
 class ConversationVariableUpdaterImpl:
     def update(self, conversation_id: str, variable: Variable):
@@ -16,7 +14,7 @@ class ConversationVariableUpdaterImpl:
         with Session(db.engine) as session:
             row = session.scalar(stmt)
             if not row:
-                raise VariableOperatorNodeError("conversation variable not found in the database")
+                raise ValueError("conversation variable not found in the database")
             row.data = variable.model_dump_json()
             session.commit()