diff --git a/web/app/components/workflow/block-selector/blocks.tsx b/web/app/components/workflow/block-selector/blocks.tsx
index 829ff64377..764fb46f02 100644
--- a/web/app/components/workflow/block-selector/blocks.tsx
+++ b/web/app/components/workflow/block-selector/blocks.tsx
@@ -19,10 +19,12 @@ import Tooltip from '@/app/components/base/tooltip'
 type BlocksProps = {
   searchText: string
   onSelect: (type: BlockEnum, tool?: ToolDefaultValue) => void
+  availableBlocksTypes?: BlockEnum[]
 }
 const Blocks = ({
   searchText,
   onSelect,
+  availableBlocksTypes = [],
 }: BlocksProps) => {
   const { t } = useTranslation()
   const isChatMode = useIsChatMode()
@@ -35,7 +37,7 @@ const Blocks = ({
         if (block.type === BlockEnum.Answer && !isChatMode)
           return false
 
-        return block.title.toLowerCase().includes(searchText.toLowerCase())
+        return block.title.toLowerCase().includes(searchText.toLowerCase()) && availableBlocksTypes.includes(block.type)
       })
 
       return {
@@ -43,7 +45,7 @@ const Blocks = ({
         [classification]: list,
       }
     }, {} as Record<string, typeof blocks>)
-  }, [blocks, isChatMode, searchText])
+  }, [blocks, isChatMode, searchText, availableBlocksTypes])
   const isEmpty = Object.values(groups).every(list => !list.length)
 
   const renderGroup = useCallback((classification: string) => {
diff --git a/web/app/components/workflow/block-selector/index.tsx b/web/app/components/workflow/block-selector/index.tsx
index 46ab16dd32..6b948a86fa 100644
--- a/web/app/components/workflow/block-selector/index.tsx
+++ b/web/app/components/workflow/block-selector/index.tsx
@@ -12,6 +12,7 @@ import type {
   OffsetOptions,
   Placement,
 } from '@floating-ui/react'
+import type { BlockEnum, OnSelectBlock } from '../types'
 import Tabs from './tabs'
 import {
   PortalToFollowElem,
@@ -22,7 +23,6 @@ import {
   Plus02,
   SearchLg,
 } from '@/app/components/base/icons/src/vender/line/general'
-import type { OnSelectBlock } from '@/app/components/workflow/types'
 import { XCircle } from '@/app/components/base/icons/src/vender/solid/general'
 
 type NodeSelectorProps = {
@@ -36,6 +36,7 @@ type NodeSelectorProps = {
   triggerClassName?: (open: boolean) => string
   popupClassName?: string
   asChild?: boolean
+  availableBlocksTypes?: BlockEnum[]
 }
 const NodeSelector: FC<NodeSelectorProps> = ({
   open: openFromProps,
@@ -48,6 +49,7 @@ const NodeSelector: FC<NodeSelectorProps> = ({
   triggerStyle,
   popupClassName,
   asChild,
+  availableBlocksTypes,
 }) => {
   const { t } = useTranslation()
   const [searchText, setSearchText] = useState('')
@@ -125,6 +127,7 @@ const NodeSelector: FC<NodeSelectorProps> = ({
           <Tabs
             onSelect={handleSelect}
             searchText={searchText}
+            availableBlocksTypes={availableBlocksTypes}
           />
         </div>
       </PortalToFollowElemContent>
diff --git a/web/app/components/workflow/block-selector/tabs.tsx b/web/app/components/workflow/block-selector/tabs.tsx
index 5e6a31c072..e717461c1c 100644
--- a/web/app/components/workflow/block-selector/tabs.tsx
+++ b/web/app/components/workflow/block-selector/tabs.tsx
@@ -13,10 +13,12 @@ import Blocks from './blocks'
 export type TabsProps = {
   searchText: string
   onSelect: (type: BlockEnum, tool?: ToolDefaultValue) => void
+  availableBlocksTypes?: BlockEnum[]
 }
 const Tabs: FC<TabsProps> = ({
   searchText,
   onSelect,
+  availableBlocksTypes,
 }) => {
   const tabs = useTabs()
   const [activeTab, setActiveTab] = useState(tabs[0].key)
@@ -46,6 +48,7 @@ const Tabs: FC<TabsProps> = ({
           <Blocks
             searchText={searchText}
             onSelect={onSelect}
+            availableBlocksTypes={availableBlocksTypes}
           />
         )
       }
diff --git a/web/app/components/workflow/constants.ts b/web/app/components/workflow/constants.ts
index 323f800c26..494d429a82 100644
--- a/web/app/components/workflow/constants.ts
+++ b/web/app/components/workflow/constants.ts
@@ -13,59 +13,128 @@ import ToolDefault from './nodes/tool/default'
 import VariableAssignerDefault from './nodes/variable-assigner/default'
 import EndNodeDefault from './nodes/end/default'
 
-export const NODES_EXTRA_DATA = {
+type NodesExtraData = {
+  author: string
+  about: string
+  availablePrevNodes: BlockEnum[]
+  availableNextNodes: BlockEnum[]
+  getAvailablePrevNodes: (isChatMode: boolean) => BlockEnum[]
+  getAvailableNextNodes: (isChatMode: boolean) => BlockEnum[]
+  checkValid: any
+}
+export const NODES_EXTRA_DATA: Record<BlockEnum, NodesExtraData> = {
   [BlockEnum.Start]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: StartNodeDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: StartNodeDefault.getAvailableNextNodes,
+    checkValid: StartNodeDefault.checkValid,
   },
   [BlockEnum.End]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: EndNodeDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: EndNodeDefault.getAvailableNextNodes,
+    checkValid: EndNodeDefault.checkValid,
   },
   [BlockEnum.Answer]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: AnswerDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: AnswerDefault.getAvailableNextNodes,
+    checkValid: AnswerDefault.checkValid,
   },
   [BlockEnum.LLM]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: LLMDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: LLMDefault.getAvailableNextNodes,
+    checkValid: LLMDefault.checkValid,
   },
   [BlockEnum.KnowledgeRetrieval]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: KnowledgeRetrievalDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: KnowledgeRetrievalDefault.getAvailableNextNodes,
+    checkValid: KnowledgeRetrievalDefault.checkValid,
   },
   [BlockEnum.IfElse]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: IfElseDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: IfElseDefault.getAvailableNextNodes,
+    checkValid: IfElseDefault.checkValid,
   },
   [BlockEnum.Code]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: CodeDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: CodeDefault.getAvailableNextNodes,
+    checkValid: CodeDefault.checkValid,
   },
   [BlockEnum.TemplateTransform]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: TemplateTransformDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: TemplateTransformDefault.getAvailableNextNodes,
+    checkValid: TemplateTransformDefault.checkValid,
   },
   [BlockEnum.QuestionClassifier]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: QuestionClassifierDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: QuestionClassifierDefault.getAvailableNextNodes,
+    checkValid: QuestionClassifierDefault.checkValid,
   },
   [BlockEnum.HttpRequest]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: HttpRequestDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: HttpRequestDefault.getAvailableNextNodes,
+    checkValid: HttpRequestDefault.checkValid,
   },
   [BlockEnum.VariableAssigner]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: VariableAssignerDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: VariableAssignerDefault.getAvailableNextNodes,
+    checkValid: VariableAssignerDefault.checkValid,
   },
   [BlockEnum.Tool]: {
     author: 'Dify',
     about: '',
+    availablePrevNodes: [],
+    availableNextNodes: [],
+    getAvailablePrevNodes: ToolDefault.getAvailablePrevNodes,
+    getAvailableNextNodes: ToolDefault.getAvailableNextNodes,
+    checkValid: ToolDefault.checkValid,
   },
 }
 
-export const ALL_CHAT_AVAILABLE_BLOCKS = Object.keys(NODES_EXTRA_DATA).filter(key => key !== BlockEnum.End) as BlockEnum[]
-export const ALL_COMPLETION_AVAILABLE_BLOCKS = Object.keys(NODES_EXTRA_DATA).filter(key => key !== BlockEnum.Answer) as BlockEnum[]
+export const ALL_CHAT_AVAILABLE_BLOCKS = Object.keys(NODES_EXTRA_DATA).filter(key => key !== BlockEnum.End && key !== BlockEnum.Start) as BlockEnum[]
+export const ALL_COMPLETION_AVAILABLE_BLOCKS = Object.keys(NODES_EXTRA_DATA).filter(key => key !== BlockEnum.Answer && key !== BlockEnum.Start) as BlockEnum[]
 
 export const NODES_INITIAL_DATA = {
   [BlockEnum.Start]: {
diff --git a/web/app/components/workflow/hooks/use-nodes-data.ts b/web/app/components/workflow/hooks/use-nodes-data.ts
index 8a1ab815cb..9eaa40ce3c 100644
--- a/web/app/components/workflow/hooks/use-nodes-data.ts
+++ b/web/app/components/workflow/hooks/use-nodes-data.ts
@@ -7,6 +7,7 @@ import {
   NODES_INITIAL_DATA,
 } from '../constants'
 import { useStore } from '../store'
+import { useIsChatMode } from './use-workflow'
 
 export const useNodesInitialData = () => {
   const { t } = useTranslation()
@@ -28,10 +29,13 @@ export const useNodesInitialData = () => {
 
 export const useNodesExtraData = () => {
   const { t } = useTranslation()
+  const isChatMode = useIsChatMode()
 
   return useMemo(() => produce(NODES_EXTRA_DATA, (draft) => {
     Object.keys(draft).forEach((key) => {
       draft[key as BlockEnum].about = t(`workflow.blocksAbout.${key}`)
+      draft[key as BlockEnum].availablePrevNodes = draft[key as BlockEnum].getAvailablePrevNodes(isChatMode)
+      draft[key as BlockEnum].availableNextNodes = draft[key as BlockEnum].getAvailableNextNodes(isChatMode)
     })
-  }), [t])
+  }), [t, isChatMode])
 }
diff --git a/web/app/components/workflow/hooks/use-workflow.ts b/web/app/components/workflow/hooks/use-workflow.ts
index 4da89fdf5d..ee2a5bb303 100644
--- a/web/app/components/workflow/hooks/use-workflow.ts
+++ b/web/app/components/workflow/hooks/use-workflow.ts
@@ -96,13 +96,7 @@ export const useWorkflow = () => {
     list.push(...incomers)
 
     return list.filter((item) => {
-      if (item.data.type === BlockEnum.IfElse)
-        return false
-
-      if (item.data.type === BlockEnum.QuestionClassifier)
-        return false
-
-      return true
+      return SUPPORT_OUTPUT_VARS_NODE.includes(item.data.type)
     })
   }, [store])
 
@@ -175,21 +169,16 @@ export const useWorkflow = () => {
     return list
   }, [store])
 
-  const getIncomersNodes = useCallback((currentNode: Node) => {
-    const {
-      getNodes,
-      edges,
-    } = store.getState()
-
-    return getIncomers(currentNode, getNodes(), edges)
-  }, [store])
+  const isValidConnection = useCallback(() => {
+    return true
+  }, [])
 
   return {
     handleLayout,
     getTreeLeafNodes,
     getBeforeNodesInSameBranch,
     getAfterNodesInSameBranch,
-    getIncomersNodes,
+    isValidConnection,
   }
 }
 
diff --git a/web/app/components/workflow/index.tsx b/web/app/components/workflow/index.tsx
index 35a26338c6..54b572b169 100644
--- a/web/app/components/workflow/index.tsx
+++ b/web/app/components/workflow/index.tsx
@@ -10,6 +10,7 @@ import ReactFlow, {
   Background,
   ReactFlowProvider,
   useOnViewportChange,
+  useStoreApi,
 } from 'reactflow'
 import type { Viewport } from 'reactflow'
 import 'reactflow/dist/style.css'
@@ -21,6 +22,7 @@ import {
   useEdgesInteractions,
   useNodesInteractions,
   useNodesSyncDraft,
+  useWorkflow,
   useWorkflowInit,
 } from './hooks'
 import Header from './header'
@@ -60,6 +62,7 @@ const Workflow: FC<WorkflowProps> = memo(({
   const showFeaturesPanel = useStore(state => state.showFeaturesPanel)
   const runningStatus = useStore(s => s.runningStatus)
   const { handleSyncWorkflowDraft } = useNodesSyncDraft()
+  const store = useStoreApi()
 
   useEffect(() => {
     setAutoFreeze(false)
@@ -84,6 +87,7 @@ const Workflow: FC<WorkflowProps> = memo(({
     handleEdgeDelete,
     handleEdgesChange,
   } = useEdgesInteractions()
+  const { isValidConnection } = useWorkflow()
 
   useOnViewportChange({
     onEnd: () => handleSyncWorkflowDraft(),
@@ -130,6 +134,7 @@ const Workflow: FC<WorkflowProps> = memo(({
         zoomOnPinch={!runningStatus}
         zoomOnScroll={!runningStatus}
         zoomOnDoubleClick={!runningStatus}
+        isValidConnection={isValidConnection}
       >
         <Background
           gap={[14, 14]}
diff --git a/web/app/components/workflow/nodes/_base/components/next-step/add.tsx b/web/app/components/workflow/nodes/_base/components/next-step/add.tsx
index 9a97502273..b1ceed244f 100644
--- a/web/app/components/workflow/nodes/_base/components/next-step/add.tsx
+++ b/web/app/components/workflow/nodes/_base/components/next-step/add.tsx
@@ -3,23 +3,33 @@ import {
   useCallback,
 } from 'react'
 import { useTranslation } from 'react-i18next'
-import { useNodesInteractions } from '@/app/components/workflow/hooks'
+import {
+  useNodesExtraData,
+  useNodesInteractions,
+} from '@/app/components/workflow/hooks'
 import BlockSelector from '@/app/components/workflow/block-selector'
 import { Plus } from '@/app/components/base/icons/src/vender/line/general'
-import type { OnSelectBlock } from '@/app/components/workflow/types'
+import type {
+  BlockEnum,
+  OnSelectBlock,
+} from '@/app/components/workflow/types'
 
 type AddProps = {
   nodeId: string
+  nodeType: BlockEnum
   sourceHandle: string
   branchName?: string
 }
 const Add = ({
   nodeId,
+  nodeType,
   sourceHandle,
   branchName,
 }: AddProps) => {
   const { t } = useTranslation()
   const { handleNodeAdd } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
+  const availableNextNodes = nodesExtraData[nodeType].availableNextNodes
 
   const handleSelect = useCallback<OnSelectBlock>((type, toolDefaultValue) => {
     handleNodeAdd(
@@ -65,6 +75,7 @@ const Add = ({
       offset={0}
       trigger={renderTrigger}
       popupClassName='!w-[328px]'
+      availableBlocksTypes={availableNextNodes}
     />
   )
 }
diff --git a/web/app/components/workflow/nodes/_base/components/next-step/index.tsx b/web/app/components/workflow/nodes/_base/components/next-step/index.tsx
index f34b5d8e60..f0cb6802af 100644
--- a/web/app/components/workflow/nodes/_base/components/next-step/index.tsx
+++ b/web/app/components/workflow/nodes/_base/components/next-step/index.tsx
@@ -51,6 +51,7 @@ const NextStep = ({
           !nodeWithBranches && !outgoers.length && (
             <Add
               nodeId={selectedNode!.id}
+              nodeType={selectedNode!.data.type}
               sourceHandle='source'
             />
           )
@@ -81,6 +82,7 @@ const NextStep = ({
                       <Add
                         key={branch.id}
                         nodeId={selectedNode!.id}
+                        nodeType={selectedNode!.data.type}
                         sourceHandle={branch.id}
                         branchName={branch.name}
                       />
diff --git a/web/app/components/workflow/nodes/_base/components/next-step/item.tsx b/web/app/components/workflow/nodes/_base/components/next-step/item.tsx
index 7a112a1403..3c62026898 100644
--- a/web/app/components/workflow/nodes/_base/components/next-step/item.tsx
+++ b/web/app/components/workflow/nodes/_base/components/next-step/item.tsx
@@ -3,13 +3,17 @@ import {
   useCallback,
 } from 'react'
 import { useTranslation } from 'react-i18next'
+import { union } from 'lodash-es'
 import type {
   CommonNodeType,
   OnSelectBlock,
 } from '@/app/components/workflow/types'
 import BlockIcon from '@/app/components/workflow/block-icon'
 import BlockSelector from '@/app/components/workflow/block-selector'
-import { useNodesInteractions } from '@/app/components/workflow/hooks'
+import {
+  useNodesExtraData,
+  useNodesInteractions,
+} from '@/app/components/workflow/hooks'
 import Button from '@/app/components/base/button'
 
 type ItemProps = {
@@ -26,6 +30,9 @@ const Item = ({
 }: ItemProps) => {
   const { t } = useTranslation()
   const { handleNodeChange } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
+  const availablePrevNodes = nodesExtraData[data.type].availablePrevNodes
+  const availableNextNodes = nodesExtraData[data.type].availableNextNodes
   const handleSelect = useCallback<OnSelectBlock>((type, toolDefaultValue) => {
     handleNodeChange(nodeId, type, sourceHandle, toolDefaultValue)
   }, [nodeId, sourceHandle, handleNodeChange])
@@ -68,6 +75,7 @@ const Item = ({
         }}
         trigger={renderTrigger}
         popupClassName='!w-[328px]'
+        availableBlocksTypes={union(availablePrevNodes, availableNextNodes)}
       />
     </div>
   )
diff --git a/web/app/components/workflow/nodes/_base/components/node-handle.tsx b/web/app/components/workflow/nodes/_base/components/node-handle.tsx
index 7b87e7e0ef..84f99c56bc 100644
--- a/web/app/components/workflow/nodes/_base/components/node-handle.tsx
+++ b/web/app/components/workflow/nodes/_base/components/node-handle.tsx
@@ -13,7 +13,10 @@ import { BlockEnum } from '../../../types'
 import type { Node } from '../../../types'
 import BlockSelector from '../../../block-selector'
 import type { ToolDefaultValue } from '../../../block-selector/types'
-import { useNodesInteractions } from '../../../hooks'
+import {
+  useNodesExtraData,
+  useNodesInteractions,
+} from '../../../hooks'
 import { useStore } from '../../../store'
 
 type NodeHandleProps = {
@@ -31,7 +34,10 @@ export const NodeTargetHandle = memo(({
 }: NodeHandleProps) => {
   const [open, setOpen] = useState(false)
   const { handleNodeAdd } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
   const connected = data._connectedTargetHandleIds?.includes(handleId)
+  const availablePrevNodes = nodesExtraData[data.type].availablePrevNodes
+  const isConnectable = !!availablePrevNodes.length
 
   const handleOpenChange = useCallback((v: boolean) => {
     setOpen(v)
@@ -67,11 +73,11 @@ export const NodeTargetHandle = memo(({
           ${data.type === BlockEnum.Start && 'opacity-0'}
           ${handleClassName}
         `}
-        isConnectable={data.type !== BlockEnum.Start}
+        isConnectable={isConnectable}
         onClick={handleHandleClick}
       >
         {
-          !connected && data.type !== BlockEnum.Start && (
+          !connected && isConnectable && (
             <BlockSelector
               open={open}
               onOpenChange={handleOpenChange}
@@ -84,6 +90,7 @@ export const NodeTargetHandle = memo(({
                 group-hover:flex
                 ${open && '!flex'}
               `}
+              availableBlocksTypes={availablePrevNodes}
             />
           )
         }
@@ -103,6 +110,9 @@ export const NodeSourceHandle = memo(({
   const notInitialWorkflow = useStore(s => s.notInitialWorkflow)
   const [open, setOpen] = useState(false)
   const { handleNodeAdd } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
+  const availableNextNodes = nodesExtraData[data.type].availableNextNodes
+  const isConnectable = !!availableNextNodes.length
   const connected = data._connectedSourceHandleIds?.includes(handleId)
   const handleOpenChange = useCallback((v: boolean) => {
     setOpen(v)
@@ -142,10 +152,11 @@ export const NodeSourceHandle = memo(({
           ${!connected && 'after:opacity-0'}
           ${handleClassName}
         `}
+        isConnectable={isConnectable}
         onClick={handleHandleClick}
       >
         {
-          !connected && (
+          !connected && isConnectable && (
             <BlockSelector
               open={open}
               onOpenChange={handleOpenChange}
@@ -157,6 +168,7 @@ export const NodeSourceHandle = memo(({
                 group-hover:flex
                 ${open && '!flex'}
               `}
+              availableBlocksTypes={availableNextNodes}
             />
           )
         }
diff --git a/web/app/components/workflow/nodes/_base/components/panel-operator/change-block.tsx b/web/app/components/workflow/nodes/_base/components/panel-operator/change-block.tsx
index c5071f057c..21d1b4d776 100644
--- a/web/app/components/workflow/nodes/_base/components/panel-operator/change-block.tsx
+++ b/web/app/components/workflow/nodes/_base/components/panel-operator/change-block.tsx
@@ -3,20 +3,32 @@ import {
   useCallback,
 } from 'react'
 import { useTranslation } from 'react-i18next'
+import { union } from 'lodash-es'
 import BlockSelector from '@/app/components/workflow/block-selector'
-import { useNodesInteractions } from '@/app/components/workflow/hooks'
-import type { OnSelectBlock } from '@/app/components/workflow/types'
+import {
+  useNodesExtraData,
+  useNodesInteractions,
+} from '@/app/components/workflow/hooks'
+import type {
+  BlockEnum,
+  OnSelectBlock,
+} from '@/app/components/workflow/types'
 
 type ChangeBlockProps = {
   nodeId: string
+  nodeType: BlockEnum
   sourceHandle: string
 }
 const ChangeBlock = ({
   nodeId,
+  nodeType,
   sourceHandle,
 }: ChangeBlockProps) => {
   const { t } = useTranslation()
   const { handleNodeChange } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
+  const availablePrevNodes = nodesExtraData[nodeType].availablePrevNodes
+  const availableNextNodes = nodesExtraData[nodeType].availableNextNodes
 
   const handleSelect = useCallback<OnSelectBlock>((type, toolDefaultValue) => {
     handleNodeChange(nodeId, type, sourceHandle, toolDefaultValue)
@@ -39,6 +51,7 @@ const ChangeBlock = ({
       }}
       onSelect={handleSelect}
       trigger={renderTrigger}
+      availableBlocksTypes={union(availablePrevNodes, availableNextNodes)}
     />
   )
 }
diff --git a/web/app/components/workflow/nodes/_base/components/panel-operator/index.tsx b/web/app/components/workflow/nodes/_base/components/panel-operator/index.tsx
index 4e4a4a414e..c00a986e91 100644
--- a/web/app/components/workflow/nodes/_base/components/panel-operator/index.tsx
+++ b/web/app/components/workflow/nodes/_base/components/panel-operator/index.tsx
@@ -129,6 +129,7 @@ const PanelOperator = ({
               data.type !== BlockEnum.Start && (
                 <ChangeBlock
                   nodeId={id}
+                  nodeType={data.type}
                   sourceHandle={edge?.sourceHandle || 'source'}
                 />
               )
diff --git a/web/app/components/workflow/nodes/_base/panel.tsx b/web/app/components/workflow/nodes/_base/panel.tsx
index 059b8bfee8..c29125daf4 100644
--- a/web/app/components/workflow/nodes/_base/panel.tsx
+++ b/web/app/components/workflow/nodes/_base/panel.tsx
@@ -20,6 +20,7 @@ import {
 import BlockIcon from '@/app/components/workflow/block-icon'
 import {
   useNodeDataUpdate,
+  useNodesExtraData,
   useNodesInteractions,
 } from '@/app/components/workflow/hooks'
 import { canRunBySingle } from '@/app/components/workflow/utils'
@@ -27,7 +28,6 @@ import { GitBranch01 } from '@/app/components/base/icons/src/vender/line/develop
 import { Play } from '@/app/components/base/icons/src/vender/line/mediaAndDevices'
 import TooltipPlus from '@/app/components/base/tooltip-plus'
 import type { Node } from '@/app/components/workflow/types'
-import { BlockEnum } from '@/app/components/workflow/types'
 
 type BasePanelProps = {
   children: ReactElement
@@ -40,6 +40,9 @@ const BasePanel: FC<BasePanelProps> = ({
 }) => {
   const { t } = useTranslation()
   const { handleNodeSelect } = useNodesInteractions()
+  const nodesExtraData = useNodesExtraData()
+  const availableNextNodes = nodesExtraData[data.type].availableNextNodes
+
   const {
     handleNodeDataUpdate,
     handleNodeDataUpdateWithSyncDraft,
@@ -102,7 +105,7 @@ const BasePanel: FC<BasePanelProps> = ({
         {cloneElement(children, { id, data })}
       </div>
       {
-        data.type !== BlockEnum.End && (
+        !!availableNextNodes.length && (
           <div className='p-4 border-t-[0.5px] border-t-black/5'>
             <div className='flex items-center mb-1 text-gray-700 text-[13px] font-semibold'>
               <GitBranch01 className='mr-1 w-4 h-4' />
diff --git a/web/app/components/workflow/nodes/if-else/default.ts b/web/app/components/workflow/nodes/if-else/default.ts
index 3fbfa03d90..f81bcc2a47 100644
--- a/web/app/components/workflow/nodes/if-else/default.ts
+++ b/web/app/components/workflow/nodes/if-else/default.ts
@@ -1,4 +1,4 @@
-import type { NodeDefault } from '../../types'
+import { BlockEnum, type NodeDefault } from '../../types'
 import { type IfElseNodeType, LogicalOperator } from './types'
 import { ALL_CHAT_AVAILABLE_BLOCKS, ALL_COMPLETION_AVAILABLE_BLOCKS } from '@/app/components/workflow/constants'
 
@@ -23,7 +23,7 @@ const nodeDefault: NodeDefault<IfElseNodeType> = {
   },
   getAvailableNextNodes(isChatMode: boolean) {
     const nodes = isChatMode ? ALL_CHAT_AVAILABLE_BLOCKS : ALL_COMPLETION_AVAILABLE_BLOCKS
-    return nodes
+    return nodes.filter(type => type !== BlockEnum.VariableAssigner)
   },
   checkValid(payload: IfElseNodeType) {
     let isValid = true
diff --git a/web/app/components/workflow/nodes/question-classifier/default.ts b/web/app/components/workflow/nodes/question-classifier/default.ts
index 21ad9e00f7..13edc69577 100644
--- a/web/app/components/workflow/nodes/question-classifier/default.ts
+++ b/web/app/components/workflow/nodes/question-classifier/default.ts
@@ -1,4 +1,5 @@
 import type { NodeDefault } from '../../types'
+import { BlockEnum } from '../../types'
 import type { QuestionClassifierNodeType } from './types'
 import { ALL_CHAT_AVAILABLE_BLOCKS, ALL_COMPLETION_AVAILABLE_BLOCKS } from '@/app/components/workflow/constants'
 
@@ -21,7 +22,7 @@ const nodeDefault: NodeDefault<QuestionClassifierNodeType> = {
   },
   getAvailableNextNodes(isChatMode: boolean) {
     const nodes = isChatMode ? ALL_CHAT_AVAILABLE_BLOCKS : ALL_COMPLETION_AVAILABLE_BLOCKS
-    return nodes
+    return nodes.filter(type => type !== BlockEnum.VariableAssigner)
   },
   checkValid(payload: QuestionClassifierNodeType) {
     let isValid = true
diff --git a/web/app/components/workflow/nodes/variable-assigner/default.ts b/web/app/components/workflow/nodes/variable-assigner/default.ts
index 9f45c6861b..b2bdd77e5f 100644
--- a/web/app/components/workflow/nodes/variable-assigner/default.ts
+++ b/web/app/components/workflow/nodes/variable-assigner/default.ts
@@ -1,4 +1,5 @@
 import { type NodeDefault, VarType } from '../../types'
+import { BlockEnum } from '../../types'
 import type { VariableAssignerNodeType } from './types'
 import { ALL_CHAT_AVAILABLE_BLOCKS, ALL_COMPLETION_AVAILABLE_BLOCKS } from '@/app/components/workflow/constants'
 
@@ -9,7 +10,7 @@ const nodeDefault: NodeDefault<VariableAssignerNodeType> = {
   },
   getAvailablePrevNodes(isChatMode: boolean) {
     const nodes = isChatMode ? ALL_CHAT_AVAILABLE_BLOCKS : ALL_COMPLETION_AVAILABLE_BLOCKS
-    return nodes
+    return nodes.filter(type => type !== BlockEnum.IfElse && type !== BlockEnum.QuestionClassifier)
   },
   getAvailableNextNodes(isChatMode: boolean) {
     const nodes = isChatMode ? ALL_CHAT_AVAILABLE_BLOCKS : ALL_COMPLETION_AVAILABLE_BLOCKS