fs.watch() listener called with null filename argument

Version

main (commit 159ae48)

Platform

SunOS smartos 5.11 joyent_20260122T000642Z i86pc i386 i86pc

Subsystem

fs

What steps will reproduce the bug?

const fs = require('fs');

const watcher = fs.watch('.', {
  recursive: false // The test passes if this option is set to `true`.
});

watcher.on('change', function (event, filename) {
  console.log(event, filename);

  if (filename === 'file.txt') {
    watcher.close();
  }
});

setTimeout(function () {
  fs.writeFileSync('file.txt', 'data');
}, 100);

How often does it reproduce? Is there a required condition?

Always.

What is the expected behavior? Why is that the expected behavior?

change file.txt is written to the standard output and the process exits. This is what happens when the recursive option is set to true.

What do you see instead?

change null is written to the standard output and the process does not exit.

Additional information

No response

Luigi, I know SunOS and FreeBSD are cousins. But I'm not fully sure if they share the same kernel bug. At least FreeBSD has the exact same issue, and it is due to the kernel.

Refs: libuv/libuv#4606 (comment)

I think the same test passes on FreeBSD? I've opened this as tracking issue for #61494 (comment) and I see no failure on FreeBSD.

@lpinca

I think the same test passes on FreeBSD? I've opened this as tracking issue for #61494 (comment) and I see no failure on FreeBSD.

~~Don't trust me that much, but is that job actually doing something? https://ci.nodejs.org/job/node-test-commit-freebsd/63310/ I mean, ~5secs... and nothing under "Tests" section".~~

@lpinca See nodejs/build@0cb941b and #54576, FreeBSD is pretty much disabled.

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`fs.watch()` listener called with `null` `filename` argument #61520

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Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

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fs.watch() listener called with null filename argument #61520

Description

Version

Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior? Why is that the expected behavior?

What do you see instead?

Additional information

Activity

juanarbol commented on Jan 25, 2026

lpinca commented on Jan 25, 2026

juanarbol commented on Jan 25, 2026

github-actions commented on Jul 20, 2026

github-actions commented on Aug 20, 2026

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`fs.watch()` listener called with `null` `filename` argument #61520