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n8n - 💡(How to fix) Fix MCP Server: regenerateNodeIds bug prevents workflow updates via Claude [1 comments, 2 participants]

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n8n-io/n8n#28542•Fetched 2026-04-16 07:05:01
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LexlangaLexlanga
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LexlangaLexlangan8n-assistant[bot]n8n-assistant[bot]
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Error Message

Describe the problem/error/question

What is the error message (if any)?

The MCP server throws an internal error related to regenerateNodeIds, blocking the update. The only workaround is to export the JSON and import manually.

  • error: all

Fix Action

Fix / Workaround

Actual behavior

The MCP server throws an internal error related to regenerateNodeIds, blocking the update. The only workaround is to export the JSON and import manually.

Code Example

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)
⚠️ WARNING ⚠️ If you have sensitive data in your workflow (like API keys), please remove it before sharing.
RAW_BUFFERClick to expand / collapse
<!-- Please follow the template below. Skip the questions that are not relevant to you. -->

Describe the problem/error/question

What is the error message (if any)?

Please share your workflow/screenshots/recording

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)
⚠️ WARNING ⚠️ If you have sensitive data in your workflow (like API keys), please remove it before sharing.

Share the output returned by the last node

<!-- If you need help with data transformations, please also share your expected output. -->

What happened?

When using Claude (Anthropic) as MCP client, updating an existing workflow via the update_workflow tool fails internally due to a bug in the regenerateNodeIds function inside the n8n MCP server.

Steps to reproduce

  1. Connect n8n MCP server to Claude (claude.ai)
  2. Ask Claude to update an existing workflow using update_workflow
  3. The operation fails internally due to regenerateNodeIds

Expected behavior

Claude should be able to update workflows via MCP without errors.

Actual behavior

The MCP server throws an internal error related to regenerateNodeIds, blocking the update. The only workaround is to export the JSON and import manually.

Debug info

core

  • n8nVersion: 2.13.3
  • platform: docker (cloud)
  • nodeJsVersion: 24.13.1
  • nodeEnv: production
  • database: sqlite
  • executionMode: regular
  • concurrency: 5
  • license: enterprise (sandbox)

storage

  • success: all
  • error: all
  • progress: false
  • manual: true
  • binaryMode: filesystem

pruning

  • enabled: true
  • maxAge: 168 hours
  • maxCount: 2500 executions

client

  • userAgent: mozilla/5.0 (windows nt 10.0; win64; x64) applewebkit/537.36 (khtml, like gecko) chrome/147.0.0.0 safari/537.36
  • isTouchDevice: false

Generated at: 2026-04-15T21:29:54.290Z

extent analysis

TL;DR

The most likely fix is to update or modify the regenerateNodeIds function in the n8n MCP server to handle workflow updates correctly.

Guidance

  • Investigate the regenerateNodeIds function to identify the specific bug causing the internal error.
  • Verify that the issue is isolated to the update_workflow tool and Claude (Anthropic) as the MCP client.
  • Check the n8n MCP server logs for more detailed error messages related to regenerateNodeIds.
  • Consider temporarily exporting and importing workflows manually as a workaround until the regenerateNodeIds function is fixed.

Example

No code snippet is provided as the issue does not include specific code details.

Notes

The issue seems to be specific to the n8n MCP server and the regenerateNodeIds function, and more information about the function's implementation and the error messages would be necessary to provide a more detailed solution.

Recommendation

Apply workaround: Manually export and import workflows until the regenerateNodeIds function is fixed, as the root cause of the issue is a bug in this function and updating or modifying it may require more time and investigation.

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FAQ

Expected behavior

Claude should be able to update workflows via MCP without errors.

#api#network issue#logging issue#authentication issue#prompt issue

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