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openclaw - 💡(How to fix) Fix [Bug]: Severe event loop block (150s+) and delayed IPv4 fallback in Telegram plugin on IPv6-disabled networks [1 comments, 2 participants]

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openclaw/openclaw#75778•Fetched 2026-05-02 05:30:21
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Severe Node.js Event Loop block (150s+) and delayed IPv4 fallback in Telegram plugin on IPv6-disabled/unroutable networks.

Error Message

WARN: Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars (skip)

Root Cause

Severe Node.js Event Loop block (150s+) and delayed IPv4 fallback in Telegram plugin on IPv6-disabled/unroutable networks.

Fix Action

Fix / Workaround

The gateway freezes completely for over 2.5 minutes during startup. The Telegram plugin tries to connect to api.telegram.org using IPv6 (AAAA record), waits for system TCP timeouts (ETIMEDOUT, ENETUNREACH), and heavily blocks the Node.js event loop (reaching up to 149,787 ms delay). The built-in fallback (enabling sticky IPv4-only dispatcher) eventually triggers, but way too late — only after the gateway has been paralyzed. Additionally, the standard Node.js workaround is explicitly blocked by the addon.

2026-05-01T19:24:16.709+03:00 [ws] ⇄ res ✓ models.list 159998ms conn=ddf082df…8164 id=880449c8…dcd4
[telegram] fetch fallback: DNS-resolved IP unreachable; trying alternative Telegram API IP (codes=none, reason=request-timeout)
2026-05-01T19:24:16.789+03:00 [diagnostic] liveness warning: reasons=event_loop_delay,event_loop_utilization,cpu interval=172s eventLoopDelayP99Ms=149787 eventLoopDelayMaxMs=149787 eventLoopUtilization=1 cpuCoreRatio=0.993 active=0 waiting=0 queued=0
[telegram] fetch fallback: enabling sticky IPv4-only dispatcher (codes=ETIMEDOUT,ENETUNREACH)
WARN: Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars (skip)

Additional information Since the standard workaround is blocked by the gateway configuration (Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars, which prevents users from passing --dns-result-order=ipv4first), users have no way to mitigate this themselves. Consider implementing autoSelectFamily: true / autoSelectFamilyAttemptTimeout in your HTTP client (undici / fetch) to handle dual-stack IPv4/IPv6 gracefully and instantly.

Code Example

2026-05-01T19:24:16.709+03:00 [ws] ⇄ res ✓ models.list 159998ms conn=ddf082df…8164 id=880449c8…dcd4
[telegram] fetch fallback: DNS-resolved IP unreachable; trying alternative Telegram API IP (codes=none, reason=request-timeout)
2026-05-01T19:24:16.789+03:00 [diagnostic] liveness warning: reasons=event_loop_delay,event_loop_utilization,cpu interval=172s eventLoopDelayP99Ms=149787 eventLoopDelayMaxMs=149787 eventLoopUtilization=1 cpuCoreRatio=0.993 active=0 waiting=0 queued=0
[telegram] fetch fallback: enabling sticky IPv4-only dispatcher (codes=ETIMEDOUT,ENETUNREACH)
WARN: Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars (skip)
RAW_BUFFERClick to expand / collapse

Bug type

Behavior bug (incorrect output/state without crash)

Beta release blocker

No

Summary

Severe Node.js Event Loop block (150s+) and delayed IPv4 fallback in Telegram plugin on IPv6-disabled/unroutable networks.

Steps to reproduce

Run OpenClaw on a host/network where IPv6 is present but unroutable, or disabled at the host OS level (e.g., Home Assistant OS). Ensure the Telegram plugin is enabled. Start or restart the OpenClaw gateway. Observe the startup time and check the logs for health-monitor liveness warnings and fetch timeouts.

Expected behavior

The gateway should start quickly. The Telegram plugin should gracefully and immediately fall back to IPv4 (e.g., using autoSelectFamily: true in Node's fetch/undici) without blocking the main event loop.

Actual behavior

The gateway freezes completely for over 2.5 minutes during startup. The Telegram plugin tries to connect to api.telegram.org using IPv6 (AAAA record), waits for system TCP timeouts (ETIMEDOUT, ENETUNREACH), and heavily blocks the Node.js event loop (reaching up to 149,787 ms delay). The built-in fallback (enabling sticky IPv4-only dispatcher) eventually triggers, but way too late — only after the gateway has been paralyzed. Additionally, the standard Node.js workaround is explicitly blocked by the addon.

OpenClaw version

2026.4.29

Operating system

Home Assistant OS (Linux 6.12.77-haos) running via Docker on Intel i5 NUC.

Install method

No response

Model

openrouter/z-ai/glm-5.1

Provider / routing chain

OpenRouter

Additional provider/model setup details

No response

Logs, screenshots, and evidence

2026-05-01T19:24:16.709+03:00 [ws] ⇄ res ✓ models.list 159998ms conn=ddf082df…8164 id=880449c8…dcd4
[telegram] fetch fallback: DNS-resolved IP unreachable; trying alternative Telegram API IP (codes=none, reason=request-timeout)
2026-05-01T19:24:16.789+03:00 [diagnostic] liveness warning: reasons=event_loop_delay,event_loop_utilization,cpu interval=172s eventLoopDelayP99Ms=149787 eventLoopDelayMaxMs=149787 eventLoopUtilization=1 cpuCoreRatio=0.993 active=0 waiting=0 queued=0
[telegram] fetch fallback: enabling sticky IPv4-only dispatcher (codes=ETIMEDOUT,ENETUNREACH)
WARN: Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars (skip)

Impact and severity

High / Severe. It completely blocks the Gateway and Control UI from loading for several minutes on every restart. Network issues in one plugin shouldn't block the main event loop and paralyze the entire core.

Additional information Since the standard workaround is blocked by the gateway configuration (Reserved environment variable 'NODE_OPTIONS' cannot be overridden via gateway_env_vars, which prevents users from passing --dns-result-order=ipv4first), users have no way to mitigate this themselves. Consider implementing autoSelectFamily: true / autoSelectFamilyAttemptTimeout in your HTTP client (undici / fetch) to handle dual-stack IPv4/IPv6 gracefully and instantly.

Additional information

No response

extent analysis

TL;DR

Implement autoSelectFamily: true in the HTTP client to enable instant IPv4 fallback on IPv6 connection failures.

Guidance

  • Review the Node.js fetch or undici configuration to ensure autoSelectFamily: true is set, allowing for immediate IPv4 fallback when IPv6 connections fail.
  • Consider adding autoSelectFamilyAttemptTimeout to define a timeout for the IPv6 connection attempt, after which the client falls back to IPv4.
  • Verify that the NODE_OPTIONS environment variable is not overriding the --dns-result-order=ipv4first setting, which could prevent the desired fallback behavior.
  • Test the updated configuration on a network with unroutable or disabled IPv6 to ensure the gateway starts quickly and the Telegram plugin falls back to IPv4 without blocking the event loop.

Example

const fetch = require('undici').fetch;
// ...
const response = await fetch('https://api.telegram.org', {
  autoSelectFamily: true,
  autoSelectFamilyAttemptTimeout: 1000, // 1 second timeout
});

Notes

The provided logs indicate that the standard Node.js workaround is blocked by the gateway configuration, so an alternative solution using autoSelectFamily is proposed.

Recommendation

Apply the workaround by implementing autoSelectFamily: true in the HTTP client, as this allows for instant IPv4 fallback on IPv6 connection failures, addressing the severe event loop blockage issue.

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FAQ

Expected behavior

The gateway should start quickly. The Telegram plugin should gracefully and immediately fall back to IPv4 (e.g., using autoSelectFamily: true in Node's fetch/undici) without blocking the main event loop.

#api#callback error#environment variable#network issue#request timeout

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openclaw - 💡(How to fix) Fix [Bug]: Severe event loop block (150s+) and delayed IPv4 fallback in Telegram plugin on IPv6-disabled networks [1 comments, 2 participants]