openclaw - 💡(How to fix) Fix [Bug]: Agent listener invoked outside active run crashes Gateway (exec stdout race condition) [1 comments, 2 participants]

LegatoFP · 2026-04-08T21:57:52Z

[openclaw] Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output after the agent run tha… Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output **after** the agent run that spawned it has already completed. ## Bug Report **Version:** OpenClaw 2026.4.5 **Node:** v24.14.0 **OS:** Linux 6.8.0-106-generic (x64) — Docker container (Ubuntu), Hetzner VPS **Install method:** Docker (`ghcr.io/openclaw/openclaw:2026.4.5`) ## Description Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output **after** the agent run that spawned it has already completed. ## Error ``` Unhandled promise rejection: Error: Agent listener invoked outside active run at Agent.processEvents (pi-agent-core/src/agent.ts:533:10) at pi-agent-core/src/agent.ts:380:21 at Object.onUpdate (pi-agent-core/src/agent-loop.ts:539:7) at emitUpdate (exec-defaults.js:1524:8) at handleStdout (exec-defaults.js:1546:4) ``` ## Steps to Reproduce 1. Run a long-lived background exec process (e.g. `python3 -u script.py > log.txt 2>&1 &`) 2. Agent run completes (session returns control) 3. Background process continues emitting stdout after the run closes 4. Gateway crashes with unhandled promise rejection ## Timeline (from this instance) - 21:42:40 UTC: Crash — stdout callback fired on completed run - 21:42:41 UTC: Container exited - 21:42:41 UTC: Docker `unless-stopped` auto-restarted - 21:44:07 UTC: Gateway ready - 21:45:57 UTC: Health check passed This crash has occurred **5 times** in our current log rotation: - 2026-04-07 16:10:20 (handleStdout) - 2026-04-07 19:32:24 (handleStderr) - 2026-04-07 19:37:42 (handleStdout) - 2026-04-08 05:45:58 (handleStdout) - 2026-04-08 21:42:40 (handleStdout) ## Expected Behavior Gateway should guard against late stdout/stderr callbacks on completed runs — catch the rejection gracefully and continue running rather than crashing the entire process. ## Impact - **Severity:** Critical (full gateway crash) - **Frequency:** Multiple times per day when background exec processes are in use - **Recovery:** Auto-restart via Docker policy (~2 min downtime) - **Related issues:** #62342, #62137, #61592, #62256, #61733 CC: @vincentkoc @mariozechner

openclaw2026-04-08 21:57:52

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openclaw/openclaw#63390•Fetched 2026-04-09 07:54:22

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Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output after the agent run that spawned it has already completed.

Error Message

Unhandled promise rejection: Error: Agent listener invoked outside active run
  at Agent.processEvents (pi-agent-core/src/agent.ts:533:10)
  at pi-agent-core/src/agent.ts:380:21
  at Object.onUpdate (pi-agent-core/src/agent-loop.ts:539:7)
  at emitUpdate (exec-defaults.js:1524:8)
  at handleStdout (exec-defaults.js:1546:4)

Root Cause

Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output after the agent run that spawned it has already completed.

Code Example

Unhandled promise rejection: Error: Agent listener invoked outside active run
  at Agent.processEvents (pi-agent-core/src/agent.ts:533:10)
  at pi-agent-core/src/agent.ts:380:21
  at Object.onUpdate (pi-agent-core/src/agent-loop.ts:539:7)
  at emitUpdate (exec-defaults.js:1524:8)
  at handleStdout (exec-defaults.js:1546:4)

RAW_BUFFERClick to expand / collapse

Bug Report

Version: OpenClaw 2026.4.5 Node: v24.14.0 OS: Linux 6.8.0-106-generic (x64) — Docker container (Ubuntu), Hetzner VPS Install method: Docker (ghcr.io/openclaw/openclaw:2026.4.5)

Description

Gateway crashes intermittently with an unhandled promise rejection when a background exec process emits stdout/stderr output after the agent run that spawned it has already completed.

Error

Unhandled promise rejection: Error: Agent listener invoked outside active run
  at Agent.processEvents (pi-agent-core/src/agent.ts:533:10)
  at pi-agent-core/src/agent.ts:380:21
  at Object.onUpdate (pi-agent-core/src/agent-loop.ts:539:7)
  at emitUpdate (exec-defaults.js:1524:8)
  at handleStdout (exec-defaults.js:1546:4)

Steps to Reproduce

Run a long-lived background exec process (e.g. python3 -u script.py > log.txt 2>&1 &)
Agent run completes (session returns control)
Background process continues emitting stdout after the run closes
Gateway crashes with unhandled promise rejection

Timeline (from this instance)

21:42:40 UTC: Crash — stdout callback fired on completed run
21:42:41 UTC: Container exited
21:42:41 UTC: Docker unless-stopped auto-restarted
21:44:07 UTC: Gateway ready
21:45:57 UTC: Health check passed

This crash has occurred 5 times in our current log rotation:

2026-04-07 16:10:20 (handleStdout)
2026-04-07 19:32:24 (handleStderr)
2026-04-07 19:37:42 (handleStdout)
2026-04-08 05:45:58 (handleStdout)
2026-04-08 21:42:40 (handleStdout)

Expected Behavior

Gateway should guard against late stdout/stderr callbacks on completed runs — catch the rejection gracefully and continue running rather than crashing the entire process.

Impact

Severity: Critical (full gateway crash)
Frequency: Multiple times per day when background exec processes are in use
Recovery: Auto-restart via Docker policy (~2 min downtime)
Related issues: #62342, #62137, #61592, #62256, #61733

CC: @vincentkoc @mariozechner

extent analysis

TL;DR

The gateway crash can be mitigated by implementing a check to ignore stdout/stderr callbacks from background exec processes after the agent run has completed.

Guidance

Review the Agent.processEvents function in pi-agent-core/src/agent.ts to determine why it's not handling the promise rejection gracefully.
Consider adding a check in handleStdout and handleStderr functions in exec-defaults.js to ignore callbacks from completed runs.
Investigate the agent-loop.ts file to see if there's a way to prevent the onUpdate function from being called after a run has completed.
Look into the related issues (#62342, #62137, #61592, #62256, #61733) to see if they provide any insight into the problem or potential solutions.

Example

// In exec-defaults.js
function handleStdout(data) {
  // Check if the run is still active before processing the stdout
  if (isRunActive()) {
    // Process the stdout
    emitUpdate(data);
  } else {
    // Ignore the stdout if the run is not active
    console.log('Ignoring stdout from completed run');
  }
}

Notes

The provided error stack suggests that the issue is related to the handling of stdout/stderr callbacks from background exec processes.
The fact that the gateway crashes with an unhandled promise rejection indicates that the error is not being properly caught and handled.

Recommendation

Apply a workaround by adding checks to ignore stdout/stderr callbacks from completed runs, as this will prevent the gateway from crashing and allow it to continue running until a more permanent fix can be implemented.

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openclaw - 💡(How to fix) Fix [Bug]: Agent listener invoked outside active run crashes Gateway (exec stdout race condition) [1 comments, 2 participants]

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