Bad reporting unsettled top-level await

[lwr]

Version

v23.11.0

Platform

Darwin 24.4.0 Darwin Kernel Version 24.4.0: Fri Apr 11 18:32:05 PDT 2025; root:xnu-11417.101.15~117/RELEASE_ARM64_T8132 arm64

Subsystem

No response

What steps will reproduce the bug?

Files

• package.json:

  {"type": "module"}

• test.js:

  export const one = 1;
  export const two = await 2;
  Promise.resolve().then(async () => {
      console.log({...await import(import.meta.url)});
  });

run test.js

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

100% reproducible

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

Outputs It works: { one: 1, two: 2 }

the async execution code block inside promise then should be executed normally

What do you see instead?

Warning: Detected unsettled top-level await at file:///path/to/test.js:1
export const one = 1;

And the process exited with error code 13.

Additional information

• It would be related with Top-level await + dynamic import + cyclic import causes "unsettled TLA" error #55468 but they are not the same problem
• Node 22 passes this test (v22.10.0)
• Adding simple noop statement workarounds this problem, this is a modified version which can pass the test

  export const one = 1;
  export const two = await 2;
  
  Promise.resolve().then(async () => {
      console.log('It works:', {...await import(import.meta.url)});
  });
  
  void 0; // empty statement do not work

  or even

  export const one = 1;
  export const two = await 2;
  
  void Promise.resolve().then(async () => {
      console.log('It works:', {...await import(import.meta.url)});
  });

I believed that node runtime incorrectly add await to the last statement, that is totally a mistake

export const one = 1;
export const two = await 2;
await Promise.resolve().then(async () => {
    console.log('It works:', {...await import(import.meta.url)});
});

[alblandino]

In case you haven’t seen it, this appears to be the same bug discussed in [#55468](#55468): Node v23’s loader sometimes mis-flags legitimate micro-tasks as “unsettled top-level await,” causing the warning and exit code 13. The fix landed in PR [#56872](#56872) and already works in nightly builds ≥ 24.0.0, so your script should run fine once that version is released.

Until then you can (a) stick with Node 22, or (b) add a no-op line such as void 0; after the Promise.resolve().then(...) chain—either approach prevents the loader from treating the last expression as still pending.

[lwr]

@alblandino well, I would like to mention a problem though it is unrelated to this.

I am a homebrew user, node 24 releasing is blocking for weeks by Homebrew/homebrew-core#222593 Homebrew/homebrew-core#222905 Homebrew/homebrew-core#223502

[joyeecheung]

I don't think this is related to #56872 which only deals with this not surfacing to process.exitCode. The exit code should be 13 in this case, because await import(import.meta.url) leads to a dead lock due to the cycle introduced and trying to incoorporate it into a top-level await means that it will never resolve, and a promise that never resolves does not block Node.js from exiting because Node.js exits on an empty event loop, not on empty microtask queue. This can be further simplified as:

await import(import.meta.url);
console.log('I am not executed');

This is a known caveat of dead-locked top-level await in a runtime like Node.js that has exit-on-completion semantics but a pending microtask is not considered to be blocking the process from exiting. This is what exit code 13 is invented for - to warn about this, not to block on this.

[lwr]

issue resolved

verified in v24.1.0