Bug Description

Activating any workflow with a Notion Trigger node fails immediately with a WorkflowActivationError. The workflow retries with exponential backoff (4s → 8s → 16s → 32s → 64s) then gives up and deregisters all crons. The trigger never activates.

Error in logs:

WorkflowActivationError: There was a problem activating the workflow: "this is not a Date object."
    at ActiveWorkflows.add (.../n8n-core/.../active-workflows.ts:130:11)
    at ActiveWorkflowManager.addTriggersAndPollers (...)
    at ActiveWorkflowManager.add (...)

Root Cause

In NotionTrigger.node.ts, poll() stores a moment.js object (not a native Date, not an ISO string) into webhookData.lastTimeChecked:

// packages/nodes-base/nodes/Notion/NotionTrigger.node.ts
webhookData.lastTimeChecked = moment().set({ second: 0, millisecond: 0 });
//                                     ↑ moment object, NOT a Date or string

webhookData is the workflow's staticData wrapped in an observable proxy. Any assignment to it immediately queues a save to the database. When TypeORM serializes the dirty staticData, it calls native Date.prototype methods on the stored value. A moment.js object is not a Date instance, so the native prototype throws:

TypeError: this is not a Date object.

This error propagates through runPoll() → executeTrigger(true) → activatePolling() → ActiveWorkflows.add(), where it is caught and re-wrapped as a WorkflowActivationError.

Note: once the value is persisted to the database and read back, it becomes an ISO string (moment objects serialize to ISO via .toJSON()). So the bug only fires on the first poll of a fresh activation — exactly when n8n calls executeTrigger(true) to test the trigger on activation.

Fix

One-line fix in NotionTrigger.node.ts:

- webhookData.lastTimeChecked = moment().set({ second: 0, millisecond: 0 });
+ webhookData.lastTimeChecked = moment().set({ second: 0, millisecond: 0 }).toISOString();

.toISOString() stores a plain string. The read-back path already handles strings correctly:

const lastTimeChecked = webhookData.lastTimeChecked
    ? moment(webhookData.lastTimeChecked)   // ← wraps string fine
    : moment().set({ second: 0, millisecond: 0 });

To Reproduce

1. Create a workflow with a Notion Trigger node (either pageAddedToDatabase or pagedUpdatedInDatabase)
2. Configure a valid Notion database ID with a connected integration
3. Activate the workflow
4. Observe WorkflowActivationError: "this is not a Date object." in logs, repeated with exponential backoff until the workflow gives up

Running the trigger node manually in the editor works fine — the bug only fires during workflow activation (the executeTrigger(true) test call).

Expected Behavior

Workflow activates cleanly and the Notion Trigger begins polling every minute.

Environment

• n8n version: 2.16.0 (Docker image docker.n8n.io/n8nio/n8n:stable)
• n8n-nodes-base version: 2.16.0
• Database: SQLite
• Execution mode: main (default)
• OS: macOS (Docker container)

Additional Context

The same bug likely affects both pageAddedToDatabase and pagedUpdatedInDatabase event types since both code paths share the same webhookData.lastTimeChecked assignment.