How to fix Error: kill ESRCH in Node.js

Node.jsINTERMEDIATEMEDIUM

This error occurs when attempting to kill a process that no longer exists or never existed. The ESRCH code indicates that the specified process ID (PID) cannot be found in the system.

What this error means

The ESRCH error (Error: kill ESRCH) stands for "Error: no such process" and is thrown by Node.js when calling `process.kill()` or `subprocess.kill()` on a process ID that doesn't exist in the system. This error is part of Node.js's process management API and indicates that the system cannot find a process with the given PID. The error can occur with both the parent process and child processes spawned via the `child_process` module. ESRCH is a POSIX error code that Node.js surfaces when the underlying system call to terminate a process fails because the target process cannot be located. This commonly happens in asynchronous environments where process lifecycles are managed across multiple event loop iterations.

How to fix "Error: kill ESRCH"

1Check if process exists before killing

Use process.kill(pid, 0) to test if a process exists without actually sending a kill signal. This method returns true if the process exists, or throws ESRCH if it doesn't:

javascript

function isProcessRunning(pid) {
  try {
    process.kill(pid, 0);
    return true;
  } catch (err) {
    return err.code !== 'ESRCH';
  }
}

// Use before killing
if (isProcessRunning(childPid)) {
  process.kill(childPid, 'SIGTERM');
}

This prevents the error by verifying the process exists before attempting termination.

2Wrap process.kill() in try-catch

Handle the ESRCH error gracefully instead of letting it crash your application:

javascript

try {
  process.kill(pid, 'SIGTERM');
  console.log(`Process ${pid} killed successfully`);
} catch (err) {
  if (err.code === 'ESRCH') {
    console.log(`Process ${pid} already terminated`);
  } else {
    throw err; // Re-throw unexpected errors
  }
}

This is especially important in cleanup handlers and shutdown sequences where processes may have already exited.

3Handle child process exit events properly

Listen to the 'exit' event on child processes to track their lifecycle and avoid killing already-exited processes:

javascript

const { spawn } = require('child_process');

const child = spawn('node', ['script.js']);
let childExited = false;

child.on('exit', (code, signal) => {
  childExited = true;
  console.log(`Child process exited with code ${code}`);
});

// Later in cleanup
function cleanup() {
  if (!childExited) {
    try {
      child.kill('SIGTERM');
    } catch (err) {
      if (err.code !== 'ESRCH') throw err;
    }
  }
}

Tracking process state prevents race conditions where the process exits between event loop ticks.

4Use AbortController for modern process management

Node.js 15+ supports AbortController for more reliable process cancellation:

javascript

const { spawn } = require('child_process');

const controller = new AbortController();
const { signal } = controller;

const child = spawn('node', ['long-running.js'], { signal });

// Abort cleanly without worrying about ESRCH
setTimeout(() => {
  controller.abort(); // Handles termination safely
}, 5000);

child.on('error', (err) => {
  if (err.name === 'AbortError') {
    console.log('Process aborted successfully');
  }
});

This modern API handles edge cases internally and prevents ESRCH errors from surfacing.

How to fix Error: kill ESRCH in Node.js

What this error means

Typical symptoms

Common causes

How to fix "Error: kill ESRCH"

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