openclaw - 💡(How to fix) Fix [Bug]: Session stuck in `processing` state causing infinite loop and API rate limiting [1 comments, 2 participants]

Bug type

Regression (worked before, now fails)

Beta release blocker

No

Summary

After a user message, the session gets stuck in processing state indefinitely; the model enters an infinite loop generating the same response, blocking the event loop (eventLoopUtilization=1) and triggering API rate limiting. Gateway logs confirm stuck session warnings from age=164s to age=1049s.

Steps to reproduce

1. Start OpenClaw 2026.4.26 with openclaw-weixin channel and qwen/qwen3.5-plus model.
2. Send a message via WeChat.
3. Model API response hangs or times out.
4. Session enters stuck state — confirmed by gateway logs showing stuck session: state=processing age=164s at 08:53:33.
5. Session remains stuck through upgrade to 2026.4.27 and restart — confirmed by logs showing stuck session warnings continuing from 09:26 to 10:11 (age up to 1049s).

Expected behavior

When the model API times out or hangs, the session should be automatically terminated with an error returned to the user. After a gateway restart, any stuck sessions should be cleaned up.

Actual behavior

Session remains in processing state indefinitely. The model enters an infinite loop generating the same content. Gateway logs show stuck session warnings every ~30s (age=164s at 08:53, age=1049s at 10:11). Event loop is blocked (eventLoopUtilization=1, eventLoopDelayP99Ms=129788.5). The issue persists through upgrade and restart.

OpenClaw version

2026.4.26 → 2026.4.27

Operating system

Windows Server 2022 (Windows_NT 10.0.20348)

Install method

npm global

Model

qwen/qwen3.5-plus

Provider / routing chain

openclaw-weixin → modelstudio → qwen/qwen3.5-plus

Additional provider/model setup details

Default route is openclaw-weixin → modelstudio → qwen/qwen3.5-plus. Config lives in ~/.openclaw/openclaw.json under auth.profiles and agent.model. Channel plugin: openclaw-weixin (C:\Users\Administrator.openclaw\extensions\openclaw-weixin).

Logs, screenshots, and evidence

Key log lines from C:\Users\ADMINI~1\AppData\Local\Temp\openclaw\openclaw-2026-04-30.log:

Stuck session warnings (every ~30s):
{"subsystem":"diagnostic"} "stuck session: sessionId=main sessionKey=agent:main:main state=processing age=1049s queueDepth=1"

Event loop blocking:
{"subsystem":"diagnostic"} "liveness warning: reasons=event_loop_delay,event_loop_utilization interval=136s eventLoopDelayP99Ms=129788.5 eventLoopDelayMaxMs=129788.5 eventLoopUtilization=1 cpuCoreRatio=0.599 active=1 waiting=0 queued=1"


Tool call error:
"[tools] read failed: EISDIR: illegal operation on a directory, raw_params={"path":"C:\\Users\\Administrator\\AppData\\Roaming\\npm\\node_modules\\openclaw\\docs\\diagnostics"}"


Restart failure after upgrade:
"Gateway did not become healthy after restart." "Gateway version mismatch: expected 2026.4.27, running gateway reported unavailable."

Full log file covers 08:50–10:11 UTC+8.

Impact and severity

Affected: WeChat channel users on Windows Severity: High (blocks entire session, consumes API quota, triggers rate limiting) Frequency: Observed once, but session remained stuck for 17+ minutes across upgrade/restart Consequence: User cannot use the session; excessive API calls trigger rate limiting; requires manual service restart to recover

Additional information

This is NOT a regression between specific versions — the issue started on 2026.4.26 and persisted through upgrade to 2026.4.27. The stuck session state was NOT cleared by the restart.

Possible root causes:

1. No timeout mechanism for processing state in the session state machine
2. Model API streaming response not properly terminated on timeout
3. Session state not cleaned up during gateway restart/upgrade
4. Tool call error (EISDIR) may have triggered an unhandled exception path

Suggested fixes:

1. Add timeout for processing state (recommended: 5 minutes)
2. Clean up stuck sessions on restart
3. Improve streaming response timeout handling
4. Add duplicate content detection to auto-terminate infinite loops