From fd08baf14159c50b5c3d8bf2df5cbcbc662f9919 Mon Sep 17 00:00:00 2001
From: yehorkardash <yehor.kardash@n8n.io>
Date: Tue, 9 Dec 2025 10:47:25 +0100
Subject: [PATCH] fix(core): Throw error when workflow is too big for webhook
 registration (#21860)

---
 packages/cli/src/services/cache/cache.service.ts  |  5 +++++
 .../test-webhook-registrations.service.test.ts    | 13 +++++++++++++
 .../test-webhook-registrations.service.ts         | 15 ++++++++++++++-
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/packages/cli/src/services/cache/cache.service.ts b/packages/cli/src/services/cache/cache.service.ts
index 95fa1ace2b7..a61903075b9 100644
--- a/packages/cli/src/services/cache/cache.service.ts
+++ b/packages/cli/src/services/cache/cache.service.ts
@@ -87,6 +87,11 @@ export class CacheService extends TypedEmitter<CacheEvents> {
 		return this.cache.kind === 'memory';
 	}
 
+	async exists(key: string) {
+		const ttl = await this.cache?.store.ttl(key);
+		return !!ttl;
+	}
+
 	// ----------------------------------
 	//             storing
 	// ----------------------------------
diff --git a/packages/cli/src/webhooks/__tests__/test-webhook-registrations.service.test.ts b/packages/cli/src/webhooks/__tests__/test-webhook-registrations.service.test.ts
index dbc79aa7cdd..75352e11fa3 100644
--- a/packages/cli/src/webhooks/__tests__/test-webhook-registrations.service.test.ts
+++ b/packages/cli/src/webhooks/__tests__/test-webhook-registrations.service.test.ts
@@ -20,6 +20,11 @@ describe('TestWebhookRegistrationsService', () => {
 	const webhookKey = 'GET|hello';
 	const cacheKey = 'test-webhooks';
 
+	beforeEach(() => {
+		jest.resetAllMocks();
+		cacheService.exists.mockResolvedValue(true);
+	});
+
 	describe('register()', () => {
 		test('should register a test webhook registration', async () => {
 			await registrations.register(registration);
@@ -32,6 +37,14 @@ describe('TestWebhookRegistrationsService', () => {
 
 			expect(cacheService.expire).not.toHaveBeenCalled();
 		});
+
+		test('should throw an error if the registration fails', async () => {
+			cacheService.exists.mockResolvedValue(false);
+
+			await expect(registrations.register(registration)).rejects.toThrow(
+				'Test webhook registration failed: workflow is too big. Remove pinned data',
+			);
+		});
 	});
 
 	describe('deregister()', () => {
diff --git a/packages/cli/src/webhooks/test-webhook-registrations.service.ts b/packages/cli/src/webhooks/test-webhook-registrations.service.ts
index cfdbc1143b4..13815f07dd2 100644
--- a/packages/cli/src/webhooks/test-webhook-registrations.service.ts
+++ b/packages/cli/src/webhooks/test-webhook-registrations.service.ts
@@ -1,6 +1,11 @@
 import { Service } from '@n8n/di';
 import { InstanceSettings } from 'n8n-core';
-import type { IWebhookData, IWorkflowBase, IDestinationNode } from 'n8n-workflow';
+import {
+	type IWebhookData,
+	type IWorkflowBase,
+	type IDestinationNode,
+	UserError,
+} from 'n8n-workflow';
 
 import { TEST_WEBHOOK_TIMEOUT, TEST_WEBHOOK_TIMEOUT_BUFFER } from '@/constants';
 import { CacheService } from '@/services/cache/cache.service';
@@ -44,6 +49,14 @@ export class TestWebhookRegistrationsService {
 
 		await this.cacheService.setHash(this.cacheKey, { [hashKey]: registration });
 
+		const isCached = await this.cacheService.exists(this.cacheKey);
+
+		if (!isCached) {
+			throw new UserError(
+				'Test webhook registration failed: workflow is too big. Remove pinned data',
+			);
+		}
+
 		if (this.instanceSettings.isSingleMain) return;
 
 		/**