diff --git a/apps/sim/executor/dag/builder.test.ts b/apps/sim/executor/dag/builder.test.ts
index 32bf14d0f1..39df0681a0 100644
--- a/apps/sim/executor/dag/builder.test.ts
+++ b/apps/sim/executor/dag/builder.test.ts
@@ -24,6 +24,71 @@ function createBlock(id: string, metadataId: string): SerializedBlock {
   }
 }
 
+describe('DAGBuilder disabled subflow validation', () => {
+  it('skips validation for disabled loops with no blocks inside', () => {
+    const workflow: SerializedWorkflow = {
+      version: '1',
+      blocks: [
+        createBlock('start', BlockType.STARTER),
+        { ...createBlock('loop-block', BlockType.FUNCTION), enabled: false },
+      ],
+      connections: [],
+      loops: {
+        'loop-1': {
+          id: 'loop-1',
+          nodes: [], // Empty loop - would normally throw
+          iterations: 3,
+        },
+      },
+    }
+
+    const builder = new DAGBuilder()
+    // Should not throw even though loop has no blocks inside
+    expect(() => builder.build(workflow)).not.toThrow()
+  })
+
+  it('skips validation for disabled parallels with no blocks inside', () => {
+    const workflow: SerializedWorkflow = {
+      version: '1',
+      blocks: [createBlock('start', BlockType.STARTER)],
+      connections: [],
+      loops: {},
+      parallels: {
+        'parallel-1': {
+          id: 'parallel-1',
+          nodes: [], // Empty parallel - would normally throw
+        },
+      },
+    }
+
+    const builder = new DAGBuilder()
+    // Should not throw even though parallel has no blocks inside
+    expect(() => builder.build(workflow)).not.toThrow()
+  })
+
+  it('skips validation for loops where all inner blocks are disabled', () => {
+    const workflow: SerializedWorkflow = {
+      version: '1',
+      blocks: [
+        createBlock('start', BlockType.STARTER),
+        { ...createBlock('inner-block', BlockType.FUNCTION), enabled: false },
+      ],
+      connections: [],
+      loops: {
+        'loop-1': {
+          id: 'loop-1',
+          nodes: ['inner-block'], // Has node but it's disabled
+          iterations: 3,
+        },
+      },
+    }
+
+    const builder = new DAGBuilder()
+    // Should not throw - loop is effectively disabled since all inner blocks are disabled
+    expect(() => builder.build(workflow)).not.toThrow()
+  })
+})
+
 describe('DAGBuilder human-in-the-loop transformation', () => {
   it('creates trigger nodes and rewires edges for pause blocks', () => {
     const workflow: SerializedWorkflow = {
diff --git a/apps/sim/executor/dag/builder.ts b/apps/sim/executor/dag/builder.ts
index b072faaede..5465df6342 100644
--- a/apps/sim/executor/dag/builder.ts
+++ b/apps/sim/executor/dag/builder.ts
@@ -136,17 +136,18 @@ export class DAGBuilder {
     nodes: string[] | undefined,
     type: 'Loop' | 'Parallel'
   ): void {
+    const sentinelStartId =
+      type === 'Loop' ? buildSentinelStartId(id) : buildParallelSentinelStartId(id)
+    const sentinelStartNode = dag.nodes.get(sentinelStartId)
+
+    if (!sentinelStartNode) return
+
     if (!nodes || nodes.length === 0) {
       throw new Error(
         `${type} has no blocks inside. Add at least one block to the ${type.toLowerCase()}.`
       )
     }
 
-    const sentinelStartId =
-      type === 'Loop' ? buildSentinelStartId(id) : buildParallelSentinelStartId(id)
-    const sentinelStartNode = dag.nodes.get(sentinelStartId)
-    if (!sentinelStartNode) return
-
     const hasConnections = Array.from(sentinelStartNode.outgoingEdges.values()).some((edge) =>
       nodes.includes(extractBaseBlockId(edge.target))
     )
diff --git a/apps/sim/executor/execution/engine.test.ts b/apps/sim/executor/execution/engine.test.ts
index f93ebc2068..880dc77c86 100644
--- a/apps/sim/executor/execution/engine.test.ts
+++ b/apps/sim/executor/execution/engine.test.ts
@@ -554,6 +554,413 @@ describe('ExecutionEngine', () => {
     })
   })
 
+  describe('Error handling in execution', () => {
+    it('should fail execution when a single node throws an error', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const errorNode = createMockNode('error-node', 'function')
+      startNode.outgoingEdges.set('edge1', { target: 'error-node' })
+
+      const dag = createMockDAG([startNode, errorNode])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['error-node']
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'error-node') {
+            throw new Error('Block execution failed')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('Block execution failed')
+    })
+
+    it('should stop parallel branches when one branch throws an error', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const parallelNodes = Array.from({ length: 5 }, (_, i) =>
+        createMockNode(`parallel${i}`, 'function')
+      )
+
+      parallelNodes.forEach((_, i) => {
+        startNode.outgoingEdges.set(`edge${i}`, { target: `parallel${i}` })
+      })
+
+      const dag = createMockDAG([startNode, ...parallelNodes])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return parallelNodes.map((_, i) => `parallel${i}`)
+        return []
+      })
+
+      const executedNodes: string[] = []
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          executedNodes.push(nodeId)
+          if (nodeId === 'parallel0') {
+            await new Promise((resolve) => setTimeout(resolve, 10))
+            throw new Error('Parallel branch failed')
+          }
+          await new Promise((resolve) => setTimeout(resolve, 100))
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('Parallel branch failed')
+    })
+
+    it('should capture only the first error when multiple parallel branches fail', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const parallelNodes = Array.from({ length: 3 }, (_, i) =>
+        createMockNode(`parallel${i}`, 'function')
+      )
+
+      parallelNodes.forEach((_, i) => {
+        startNode.outgoingEdges.set(`edge${i}`, { target: `parallel${i}` })
+      })
+
+      const dag = createMockDAG([startNode, ...parallelNodes])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return parallelNodes.map((_, i) => `parallel${i}`)
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'parallel0') {
+            await new Promise((resolve) => setTimeout(resolve, 10))
+            throw new Error('First error')
+          }
+          if (nodeId === 'parallel1') {
+            await new Promise((resolve) => setTimeout(resolve, 20))
+            throw new Error('Second error')
+          }
+          if (nodeId === 'parallel2') {
+            await new Promise((resolve) => setTimeout(resolve, 30))
+            throw new Error('Third error')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('First error')
+    })
+
+    it('should wait for ongoing executions to complete before throwing error', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const fastErrorNode = createMockNode('fast-error', 'function')
+      const slowNode = createMockNode('slow', 'function')
+
+      startNode.outgoingEdges.set('edge1', { target: 'fast-error' })
+      startNode.outgoingEdges.set('edge2', { target: 'slow' })
+
+      const dag = createMockDAG([startNode, fastErrorNode, slowNode])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['fast-error', 'slow']
+        return []
+      })
+
+      let slowNodeCompleted = false
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'fast-error') {
+            await new Promise((resolve) => setTimeout(resolve, 10))
+            throw new Error('Fast error')
+          }
+          if (nodeId === 'slow') {
+            await new Promise((resolve) => setTimeout(resolve, 50))
+            slowNodeCompleted = true
+            return { nodeId, output: {}, isFinalOutput: false }
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('Fast error')
+
+      expect(slowNodeCompleted).toBe(true)
+    })
+
+    it('should not queue new nodes after an error occurs', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const errorNode = createMockNode('error-node', 'function')
+      const afterErrorNode = createMockNode('after-error', 'function')
+
+      startNode.outgoingEdges.set('edge1', { target: 'error-node' })
+      errorNode.outgoingEdges.set('edge2', { target: 'after-error' })
+
+      const dag = createMockDAG([startNode, errorNode, afterErrorNode])
+      const context = createMockContext()
+
+      const queuedNodes: string[] = []
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') {
+          queuedNodes.push('error-node')
+          return ['error-node']
+        }
+        if (node.id === 'error-node') {
+          queuedNodes.push('after-error')
+          return ['after-error']
+        }
+        return []
+      })
+
+      const executedNodes: string[] = []
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          executedNodes.push(nodeId)
+          if (nodeId === 'error-node') {
+            throw new Error('Node error')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('Node error')
+
+      expect(executedNodes).not.toContain('after-error')
+    })
+
+    it('should populate error result with metadata when execution fails', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const errorNode = createMockNode('error-node', 'function')
+      startNode.outgoingEdges.set('edge1', { target: 'error-node' })
+
+      const dag = createMockDAG([startNode, errorNode])
+      const context = createMockContext()
+      context.blockLogs.push({
+        blockId: 'start',
+        blockName: 'Start',
+        blockType: 'starter',
+        startedAt: new Date().toISOString(),
+        endedAt: new Date().toISOString(),
+        durationMs: 10,
+        success: true,
+      })
+
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['error-node']
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'error-node') {
+            const error = new Error('Execution failed') as any
+            error.executionResult = {
+              success: false,
+              output: { partial: 'data' },
+              logs: context.blockLogs,
+              metadata: context.metadata,
+            }
+            throw error
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      try {
+        await engine.run('start')
+        expect.fail('Should have thrown')
+      } catch (error: any) {
+        expect(error.executionResult).toBeDefined()
+        expect(error.executionResult.metadata.endTime).toBeDefined()
+        expect(error.executionResult.metadata.duration).toBeDefined()
+      }
+    })
+
+    it('should prefer cancellation status over error when both occur', async () => {
+      const abortController = new AbortController()
+
+      const startNode = createMockNode('start', 'starter')
+      const errorNode = createMockNode('error-node', 'function')
+      startNode.outgoingEdges.set('edge1', { target: 'error-node' })
+
+      const dag = createMockDAG([startNode, errorNode])
+      const context = createMockContext({ abortSignal: abortController.signal })
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['error-node']
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'error-node') {
+            abortController.abort()
+            throw new Error('Node error')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+      const result = await engine.run('start')
+
+      expect(result.status).toBe('cancelled')
+      expect(result.success).toBe(false)
+    })
+
+    it('should stop loop iteration when error occurs in loop body', async () => {
+      const loopStartNode = createMockNode('loop-start', 'loop_sentinel')
+      loopStartNode.metadata = { isSentinel: true, sentinelType: 'start', loopId: 'loop1' }
+
+      const loopBodyNode = createMockNode('loop-body', 'function')
+      loopBodyNode.metadata = { isLoopNode: true, loopId: 'loop1' }
+
+      const loopEndNode = createMockNode('loop-end', 'loop_sentinel')
+      loopEndNode.metadata = { isSentinel: true, sentinelType: 'end', loopId: 'loop1' }
+
+      const afterLoopNode = createMockNode('after-loop', 'function')
+
+      loopStartNode.outgoingEdges.set('edge1', { target: 'loop-body' })
+      loopBodyNode.outgoingEdges.set('edge2', { target: 'loop-end' })
+      loopEndNode.outgoingEdges.set('loop_continue', {
+        target: 'loop-start',
+        sourceHandle: 'loop_continue',
+      })
+      loopEndNode.outgoingEdges.set('loop_complete', {
+        target: 'after-loop',
+        sourceHandle: 'loop_complete',
+      })
+
+      const dag = createMockDAG([loopStartNode, loopBodyNode, loopEndNode, afterLoopNode])
+      const context = createMockContext()
+
+      let iterationCount = 0
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'loop-start') return ['loop-body']
+        if (node.id === 'loop-body') return ['loop-end']
+        if (node.id === 'loop-end') {
+          iterationCount++
+          if (iterationCount < 5) return ['loop-start']
+          return ['after-loop']
+        }
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'loop-body' && iterationCount >= 2) {
+            throw new Error('Loop body error on iteration 3')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('loop-start')).rejects.toThrow('Loop body error on iteration 3')
+
+      expect(iterationCount).toBeLessThanOrEqual(3)
+    })
+
+    it('should handle error that is not an Error instance', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const errorNode = createMockNode('error-node', 'function')
+      startNode.outgoingEdges.set('edge1', { target: 'error-node' })
+
+      const dag = createMockDAG([startNode, errorNode])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['error-node']
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'error-node') {
+            throw 'String error message'
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      await expect(engine.run('start')).rejects.toThrow('String error message')
+    })
+
+    it('should preserve partial output when error occurs after some blocks complete', async () => {
+      const startNode = createMockNode('start', 'starter')
+      const successNode = createMockNode('success', 'function')
+      const errorNode = createMockNode('error-node', 'function')
+
+      startNode.outgoingEdges.set('edge1', { target: 'success' })
+      successNode.outgoingEdges.set('edge2', { target: 'error-node' })
+
+      const dag = createMockDAG([startNode, successNode, errorNode])
+      const context = createMockContext()
+      const edgeManager = createMockEdgeManager((node) => {
+        if (node.id === 'start') return ['success']
+        if (node.id === 'success') return ['error-node']
+        return []
+      })
+
+      const nodeOrchestrator = {
+        executionCount: 0,
+        executeNode: vi.fn().mockImplementation(async (_ctx: ExecutionContext, nodeId: string) => {
+          if (nodeId === 'success') {
+            return { nodeId, output: { successData: 'preserved' }, isFinalOutput: false }
+          }
+          if (nodeId === 'error-node') {
+            throw new Error('Late error')
+          }
+          return { nodeId, output: {}, isFinalOutput: false }
+        }),
+        handleNodeCompletion: vi.fn(),
+      } as unknown as MockNodeOrchestrator
+
+      const engine = new ExecutionEngine(context, dag, edgeManager, nodeOrchestrator)
+
+      try {
+        await engine.run('start')
+        expect.fail('Should have thrown')
+      } catch (error: any) {
+        // Verify the error was thrown
+        expect(error.message).toBe('Late error')
+        // The partial output should be available in executionResult if attached
+        if (error.executionResult) {
+          expect(error.executionResult.output).toBeDefined()
+        }
+      }
+    })
+  })
+
   describe('Cancellation flag behavior', () => {
     it('should set cancelledFlag when abort signal fires', async () => {
       const abortController = new AbortController()
diff --git a/apps/sim/executor/execution/engine.ts b/apps/sim/executor/execution/engine.ts
index 7c2317b047..58792ef2b8 100644
--- a/apps/sim/executor/execution/engine.ts
+++ b/apps/sim/executor/execution/engine.ts
@@ -25,6 +25,8 @@ export class ExecutionEngine {
   private pausedBlocks: Map<string, PauseMetadata> = new Map()
   private allowResumeTriggers: boolean
   private cancelledFlag = false
+  private errorFlag = false
+  private executionError: Error | null = null
   private lastCancellationCheck = 0
   private readonly useRedisCancellation: boolean
   private readonly CANCELLATION_CHECK_INTERVAL_MS = 500
@@ -103,7 +105,7 @@ export class ExecutionEngine {
       this.initializeQueue(triggerBlockId)
 
       while (this.hasWork()) {
-        if (await this.checkCancellation()) {
+        if ((await this.checkCancellation()) || this.errorFlag) {
           break
         }
         await this.processQueue()
@@ -113,6 +115,11 @@ export class ExecutionEngine {
         await this.waitForAllExecutions()
       }
 
+      // Rethrow the captured error so it's handled by the catch block
+      if (this.errorFlag && this.executionError) {
+        throw this.executionError
+      }
+
       if (this.pausedBlocks.size > 0) {
         return this.buildPausedResult(startTime)
       }
@@ -196,11 +203,17 @@ export class ExecutionEngine {
   }
 
   private trackExecution(promise: Promise<void>): void {
-    this.executing.add(promise)
-    promise.catch(() => {})
-    promise.finally(() => {
-      this.executing.delete(promise)
-    })
+    const trackedPromise = promise
+      .catch((error) => {
+        if (!this.errorFlag) {
+          this.errorFlag = true
+          this.executionError = error instanceof Error ? error : new Error(String(error))
+        }
+      })
+      .finally(() => {
+        this.executing.delete(trackedPromise)
+      })
+    this.executing.add(trackedPromise)
   }
 
   private async waitForAnyExecution(): Promise<void> {
@@ -315,7 +328,7 @@ export class ExecutionEngine {
 
   private async processQueue(): Promise<void> {
     while (this.readyQueue.length > 0) {
-      if (await this.checkCancellation()) {
+      if ((await this.checkCancellation()) || this.errorFlag) {
         break
       }
       const nodeId = this.dequeue()
@@ -324,7 +337,7 @@ export class ExecutionEngine {
       this.trackExecution(promise)
     }
 
-    if (this.executing.size > 0 && !this.cancelledFlag) {
+    if (this.executing.size > 0 && !this.cancelledFlag && !this.errorFlag) {
       await this.waitForAnyExecution()
     }
   }
diff --git a/apps/sim/executor/handlers/workflow/workflow-handler.test.ts b/apps/sim/executor/handlers/workflow/workflow-handler.test.ts
index bf304c786d..21d9cd3fdb 100644
--- a/apps/sim/executor/handlers/workflow/workflow-handler.test.ts
+++ b/apps/sim/executor/handlers/workflow/workflow-handler.test.ts
@@ -204,26 +204,21 @@ describe('WorkflowBlockHandler', () => {
       })
     })
 
-    it('should map failed child output correctly', () => {
+    it('should throw error for failed child output so BlockExecutor can check error port', () => {
       const childResult = {
         success: false,
         error: 'Child workflow failed',
       }
 
-      const result = (handler as any).mapChildOutputToParent(
-        childResult,
-        'child-id',
-        'Child Workflow',
-        100
-      )
+      expect(() =>
+        (handler as any).mapChildOutputToParent(childResult, 'child-id', 'Child Workflow', 100)
+      ).toThrow('Error in child workflow "Child Workflow": Child workflow failed')
 
-      expect(result).toEqual({
-        success: false,
-        childWorkflowName: 'Child Workflow',
-        result: {},
-        error: 'Child workflow failed',
-        childTraceSpans: [],
-      })
+      try {
+        ;(handler as any).mapChildOutputToParent(childResult, 'child-id', 'Child Workflow', 100)
+      } catch (error: any) {
+        expect(error.childTraceSpans).toEqual([])
+      }
     })
 
     it('should handle nested response structures', () => {
diff --git a/apps/sim/executor/handlers/workflow/workflow-handler.ts b/apps/sim/executor/handlers/workflow/workflow-handler.ts
index 94f0908897..d8f7ced358 100644
--- a/apps/sim/executor/handlers/workflow/workflow-handler.ts
+++ b/apps/sim/executor/handlers/workflow/workflow-handler.ts
@@ -144,6 +144,11 @@ export class WorkflowBlockHandler implements BlockHandler {
       const workflowMetadata = workflows[workflowId]
       const childWorkflowName = workflowMetadata?.name || workflowId
 
+      const originalError = error.message || 'Unknown error'
+      const wrappedError = new Error(
+        `Error in child workflow "${childWorkflowName}": ${originalError}`
+      )
+
       if (error.executionResult?.logs) {
         const executionResult = error.executionResult as ExecutionResult
 
@@ -159,28 +164,12 @@ export class WorkflowBlockHandler implements BlockHandler {
         )
 
         logger.info(`Captured ${childTraceSpans.length} child trace spans from failed execution`)
-
-        return {
-          success: false,
-          childWorkflowName,
-          result: {},
-          error: error.message || 'Child workflow execution failed',
-          childTraceSpans: childTraceSpans,
-        } as Record<string, any>
+        ;(wrappedError as any).childTraceSpans = childTraceSpans
+      } else if (error.childTraceSpans && Array.isArray(error.childTraceSpans)) {
+        ;(wrappedError as any).childTraceSpans = error.childTraceSpans
       }
 
-      if (error.childTraceSpans && Array.isArray(error.childTraceSpans)) {
-        return {
-          success: false,
-          childWorkflowName,
-          result: {},
-          error: error.message || 'Child workflow execution failed',
-          childTraceSpans: error.childTraceSpans,
-        } as Record<string, any>
-      }
-
-      const originalError = error.message || 'Unknown error'
-      throw new Error(`Error in child workflow "${childWorkflowName}": ${originalError}`)
+      throw wrappedError
     }
   }
 
@@ -452,17 +441,13 @@ export class WorkflowBlockHandler implements BlockHandler {
 
     if (!success) {
       logger.warn(`Child workflow ${childWorkflowName} failed`)
-      // Return failure with child trace spans so they can be displayed
-      return {
-        success: false,
-        childWorkflowName,
-        result,
-        error: childResult.error || 'Child workflow execution failed',
-        childTraceSpans: childTraceSpans || [],
-      } as Record<string, any>
+      const error = new Error(
+        `Error in child workflow "${childWorkflowName}": ${childResult.error || 'Child workflow execution failed'}`
+      )
+      ;(error as any).childTraceSpans = childTraceSpans || []
+      throw error
     }
 
-    // Success case
     return {
       success: true,
       childWorkflowName,