diff --git a/web/app/components/workflow/hooks/use-nodes-interactions.ts b/web/app/components/workflow/hooks/use-nodes-interactions.ts
index 523a8e9a6e..191bd7af0a 100644
--- a/web/app/components/workflow/hooks/use-nodes-interactions.ts
+++ b/web/app/components/workflow/hooks/use-nodes-interactions.ts
@@ -43,7 +43,10 @@ export const useNodesInteractions = () => {
   const workflowStore = useWorkflowStore()
   const nodesExtraData = useNodesExtraData()
   const { handleSyncWorkflowDraft } = useNodesSyncDraft()
-  const { getAfterNodesInSameBranch } = useWorkflow()
+  const {
+    getAfterNodesInSameBranch,
+    getTreeLeafNodes,
+  } = useWorkflow()
   const { getNodesReadOnly } = useNodesReadOnly()
   const dragNodeStartPosition = useRef({ x: 0, y: 0 } as { x: number; y: number })
   const connectingNodeRef = useRef<{ nodeId: string; handleType: HandleType } | null>(null)
@@ -313,6 +316,13 @@ export const useNodesInteractions = () => {
       setEdges,
     } = store.getState()
     const nodes = getNodes()
+    const targetNode = nodes.find(node => node.id === target!)
+    if (targetNode && targetNode?.data.type === BlockEnum.VariableAssigner) {
+      const treeNodes = getTreeLeafNodes(target!)
+
+      if (!treeNodes.find(treeNode => treeNode.id === source))
+        return
+    }
     const needDeleteEdges = edges.filter((edge) => {
       if (edge.source === source) {
         if (edge.sourceHandle)
@@ -368,7 +378,7 @@ export const useNodesInteractions = () => {
     })
     setEdges(newEdges)
     handleSyncWorkflowDraft()
-  }, [store, handleSyncWorkflowDraft, getNodesReadOnly])
+  }, [store, handleSyncWorkflowDraft, getNodesReadOnly, getTreeLeafNodes])
 
   const handleNodeConnectStart = useCallback<OnConnectStart>((_, { nodeId, handleType }) => {
     if (nodeId && handleType) {
diff --git a/web/app/components/workflow/nodes/variable-assigner/components/var-list/index.tsx b/web/app/components/workflow/nodes/variable-assigner/components/var-list/index.tsx
index 668a9fd012..36a34003fe 100644
--- a/web/app/components/workflow/nodes/variable-assigner/components/var-list/index.tsx
+++ b/web/app/components/workflow/nodes/variable-assigner/components/var-list/index.tsx
@@ -6,6 +6,7 @@ import produce from 'immer'
 import RemoveButton from '../../../_base/components/remove-button'
 import VarReferencePicker from '@/app/components/workflow/nodes/_base/components/variable/var-reference-picker'
 import type { ValueSelector, Var } from '@/app/components/workflow/types'
+import { VarType as VarKindType } from '@/app/components/workflow/nodes/tool/types'
 
 type Props = {
   readonly: boolean
@@ -71,6 +72,7 @@ const VarList: FC<Props> = ({
             onOpen={handleOpen(index)}
             onlyLeafNodeVar={onlyLeafNodeVar}
             filterVar={filterVar}
+            defaultVarKindType={VarKindType.variable}
           />
           {!readonly && (
             <RemoveButton
diff --git a/web/app/components/workflow/utils.ts b/web/app/components/workflow/utils.ts
index d9239a8b6d..9ba156608b 100644
--- a/web/app/components/workflow/utils.ts
+++ b/web/app/components/workflow/utils.ts
@@ -59,7 +59,7 @@ const getCycleEdges = (nodes: Node[], edges: Edge[]) => {
   }
 
   for (const edge of edges)
-    adjaList[edge.source].push(edge.target)
+    adjaList[edge.source]?.push(edge.target)
 
   for (let i = 0; i < nodes.length; i++) {
     if (color[nodes[i].id] === WHITE)
@@ -143,14 +143,14 @@ export const initialEdges = (edges: Edge[], nodes: Node[]) => {
     if (!edge.targetHandle)
       edge.targetHandle = 'target'
 
-    if (!edge.data?.sourceType) {
+    if (!edge.data?.sourceType && edge.source) {
       edge.data = {
         ...edge.data,
         sourceType: nodesMap[edge.source].data.type!,
       } as any
     }
 
-    if (!edge.data?.targetType) {
+    if (!edge.data?.targetType && edge.target) {
       edge.data = {
         ...edge.data,
         targetType: nodesMap[edge.target].data.type!,