Workflow UI crashes with 'Could not find property option' after Switch node fallbackOutput set at wrong parameter level via API

Questions
1

Describe the problem/error/question

After ~30 partial API update operations via the n8n MCP tool, my workflow can no longer be opened in the n8n UI editor. When navigating to the workflow URL, the following error appears and the editor redirects to a blank new workflow screen:

”Could not find workflow / Could not find property option”

The root cause: a Switch node (if-gate) had fallbackOutput: “none” placed at the wrong level — at the top level of parameters instead of inside options.

What is the error message?

Could not find workflow / Could not find property option

The UI immediately redirects to a blank new workflow screen. Occurs consistently in normal browser, incognito, and direct URL access.

Root Cause

Switch node (node ID: if-gate) was configured with fallbackOutput: “none” at the wrong parameter level via API:

Incorrect (what was set):

parameters.fallbackOutput = “none” ← wrong level

Correct (what it should be):

parameters.options.fallbackOutput = “none” ← correct level

Current State

  • API GET works: returns full workflow data (47 nodes, all connections intact)
    • API PUT works: successfully updated
      • Webhook endpoint is live
        • UI editor: BROKEN — crashes with “Could not find property option”
          • Workflow activation: cannot activate via UI or API

        • Attempted Fixes

        1. Browser hard refresh — no effect
          1. Incognito window with fresh login — same error
            1. Direct URL access — same error
              1. PUT API to re-save with cleaned parameters (removed fallbackOutput from wrong location) — PUT succeeds but UI error persists

            3. Questions

            1. Is this a known issue where the UI cannot parse a Switch node when fallbackOutput is placed at the top level of parameters instead of inside options?
              1. Is there a way to force the UI to re-validate/repair the workflow schema?
                1. For n8n Cloud: can the support team inspect and repair the internal node property structure?

              3. n8n Setup

              • n8n version: Latest (n8n Cloud)
                • Running via: n8n Cloud (wontaeryu.app.n8n.cloud)
                  • Workflow ID: 0FvD8fdCNthEg15l
                    • Workflow Name: echo-webhook (Schema v1)
2

@wontaeryu, the UI validator chokes when it hits fallbackOutput at the wrong nesting level and there’s no way to force a schema repair from the editor — you need to GET the workflow via API, fix the node, and PUT it back. Here’s a minimal workflow you can use as reference for the correct Switch node structure:

Swap the URLs to your actual cloud API endpoint with your API key in the header auth, the key thing is options.fallbackOutput not parameters.fallbackOutput — since you’re on cloud hit up help@n8n.io with the workflow ID if the PUT still doesn’t unstick it, they can fix it server-side.