`openAsBlob` fails synchronously

[remcohaszing]

Version

v24.14.0

Platform

Linux vali 6.18.7-76061807-generic #202601231045~1769703228~24.04~cb87b5b SMP PREEMPT_DYNAMIC Thu J x86_64 x86_64 x86_64 GNU/Linux

Subsystem

fs

What steps will reproduce the bug?

import { openAsBlob } from 'node:fs'

const result = await openAsBlob('does-not-exist').catch((error) => {})

console.log(result)

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

Always

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

I expect openAsBlob() to always return a promise. If there are any problems, I expect the promise to be rejected.

What do you see instead?

Instead of returning a promise that’s rejected, openAsBlob() fails synchronously. This means that instead of using the Promise.catch() method, you have to use try/catch logic instead.

Additional information

Just marking the function as async on https://github.com/nodejs/node/blob/v25.8.1/lib/fs.js#L570 would fix it.

[targos]

@nodejs/fs

It's a weird one. I've also always wondered why the function is on node:fs instead of node:fs/promises.

[remcohaszing]

I understand if new, modern APIs use a promise approach instead of a callback, even if they are exported from node:fs. But I have to admit I was a bit puzzled at first when I couldn’t import openAsBlob from node:fs/promises.

[Xstoudi]

Maybe it's worth mentioning #49759 as previous work on node:fs vs node:fs/promises.

The solution mentioned in additional info works. That said, moving Promise-based implementation to node:fs/promises and having a callback-based implementation in node:fs would fix the oddity of finding a Promise-based implem among callback-based functions. Not sure if it's really desirable to have a callback-based implem tho.

[mattskel]

@remcohaszing This change makes openAsBlob reliably return a Promise in all cases by converting any synchronous validation or creation errors into Promise rejections. That matches the Promise-based contract discussed in the issue, so callers can always use await/.catch without missing sync throws.

@Xstoudi Similar to #49759 to handle errors. But instead retains the promise based contract.

I’ve opened this as a draft PR to get early feedback. If reviewers agree with the approach, I’ll follow up with tests.

[damianremington274-blip]

Thank you for opening the draft PR for this. Converting the synchronous errors into Promise rejections makes sense and aligns with the expected Promise-based contract for openAsBlob. It should definitely make the behavior more predictable for callers using await or .catch.

…

On Thu, Apr 9, 2026, 11:50 AM mattskel ***@***.***> wrote: *mattskel* left a comment (nodejs/node#62418) <#62418 (comment)> @remcohaszing <https://github.com/remcohaszing> This change makes openAsBlob reliably return a Promise in all cases by converting any synchronous validation or creation errors into Promise rejections. That matches the Promise-based contract discussed in the issue, so callers can always use await/.catch without missing sync throws. @Xstoudi <https://github.com/Xstoudi> Similar to #49759 <#49759> to handle errors. But instead retains the promise based contract. I’ve opened this as a draft PR to get early feedback. If reviewers agree with the approach, I’ll follow up with tests. — Reply to this email directly, view it on GitHub <#62418 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/B7YAFGT3DXWDP6M7MUWHC5T4U7IF5AVCNFSM6AAAAACW5ORS52VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DEMJVHE3TGNRZGQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>