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openclaw - 💡(How to fix) Fix fetch failed with undici 8.0.0 on Node.js 22: per-request dispatcher incompatible with built-in fetch [3 comments, 2 participants]

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openclaw/openclaw#61448•Fetched 2026-04-08 02:58:30
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Error Message

  • Error reproduces on every call, not intermittent Error message: TypeError: fetch failed - invalid onRequestStart method

Root Cause

Node.js 22's built-in fetch uses internal undici 6.23.0. OpenClaw's fetch-guard.ts creates an undici 8.0.0 Agent via createPinnedDispatcher() and passes it as a per-request dispatcher to fetch().

undici 8.0.0 refactored the dispatcher interface (onRequestStart method signature changed), making it incompatible with Node.js 22's built-in fetch pipeline.

Error message: TypeError: fetch failed - invalid onRequestStart method

Fix Action

Workaround

  • package.json: undici ^8.0.0 → 6.23.0
  • src/infra/net/undici-global-dispatcher.ts: add as any cast on connect options (undici 6.x has stricter TypeScript types for connect than 8.x)
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Environment

  • Node.js v22.22.0 (built-in undici 6.23.0)
  • OpenClaw depends on undici ^8.0.0 (package.json)
  • OS: Ubuntu 25.10, Cloudflare WARP

Symptoms

  • tavily_search and web_search tools consistently return TypeError: fetch failed
  • curl and Node.js native fetch (without dispatcher) work fine
  • Error reproduces on every call, not intermittent

Root Cause

Node.js 22's built-in fetch uses internal undici 6.23.0. OpenClaw's fetch-guard.ts creates an undici 8.0.0 Agent via createPinnedDispatcher() and passes it as a per-request dispatcher to fetch().

undici 8.0.0 refactored the dispatcher interface (onRequestStart method signature changed), making it incompatible with Node.js 22's built-in fetch pipeline.

Error message: TypeError: fetch failed - invalid onRequestStart method

Verification

ScenarioResult
undici 8.0.0 Agent as per-request dispatcher❌ fetch failed
undici 8.0.0 Agent via setGlobalDispatcher✅ works (replaces entire dispatch chain)
No dispatcher (plain fetch)✅ works
undici 6.23.0 Agent as per-request dispatcher✅ works

All required APIs (Agent, EnvHttpProxyAgent, ProxyAgent, getGlobalDispatcher, setGlobalDispatcher) exist in undici 6.23.0.

Impact

  • All requests through withTrustedWebToolsEndpoint (Tavily search/extract, Brave search, etc.)
  • All requests using createPinnedDispatcher for SSRF protection
  • ensureGlobalUndiciStreamTimeouts sets a global dispatcher from external undici — version mismatch with built-in fetch is a latent risk even when global dispatcher appears to work

Workaround

  • package.json: undici ^8.0.0 → 6.23.0
  • src/infra/net/undici-global-dispatcher.ts: add as any cast on connect options (undici 6.x has stricter TypeScript types for connect than 8.x)

Suggested Fixes

  1. Downgrade undici version constraint to ^6.23.0 to match Node.js 22's built-in version
  2. Or detect Node.js built-in undici version at runtime and choose per-request vs global dispatcher accordingly
  3. Or wait for Node.js to ship undici 8.x before updating the dependency

Not Verified

  • Whether Node.js 23+ ships with undici 8.x (may already be fixed in newer Node.js)
  • Whether undici 8.x has a patch version addressing this compatibility issue

extent analysis

TL;DR

Downgrade the undici version constraint to ^6.23.0 to match Node.js 22's built-in version.

Guidance

  • Verify the undici version used by Node.js 22 to ensure it's indeed 6.23.0, which is incompatible with OpenClaw's undici 8.0.0 dependency.
  • Consider downgrading the undici version in package.json to ^6.23.0 as a temporary workaround to resolve the TypeError: fetch failed issue.
  • If upgrading Node.js to a version that includes undici 8.x is feasible, this could also resolve the compatibility issue.
  • Be cautious of the latent risk of version mismatches when using ensureGlobalUndiciStreamTimeouts and createPinnedDispatcher for SSRF protection.

Example

No code snippet is provided as the issue is primarily related to version compatibility and dependency management.

Notes

The suggested fixes and workarounds are based on the information provided and may not be applicable if the Node.js or undici versions are different. It's also important to note that downgrading dependencies can introduce other compatibility issues.

Recommendation

Apply the workaround by downgrading the undici version constraint to ^6.23.0 to immediately resolve the TypeError: fetch failed issue, as this is a straightforward and verified solution.

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openclaw - 💡(How to fix) Fix fetch failed with undici 8.0.0 on Node.js 22: per-request dispatcher incompatible with built-in fetch [3 comments, 2 participants]