expressjs/multer

Wrong error sometimes for file that's too large?

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#405 opened on Oct 6, 2016

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Description

Having trouble reproducing this, but for a while today I was receiving a confusing error, 'Unexpected field' (a.k.a. LIMIT_UNEXPECTED_FILE). Searching Stack Overflow I found that this error was mostly caused by a mismatch between the "name" string in the form and the one in my Express route. But that wasn't it because they were both called "image."

I tried re-installing the module but still got the same error. Then I switched to a much smaller file and Multer started working again without the "unexpected field" error. Then, to test my theory I tried uploading a large file, only this time to receive the correct "request entity too large" error.

Also I wonder if there has been discussion of providing an easier-to-understand, separate error message like

"Error: Multer requires a 'name' attribute that matches the one in the route, but received: 'picField'"

Seems like it would save a lot of time for folks...

Contributor guide

Research direction
Investigate the conditions under which Multer throws LIMIT UNEXPECTED FILE instead of LIMIT FILE SIZE for large files. Review the error handling logic in lib/multer.js and the busboy library to understand how file size limits are enforced. Consider adding a separate error code or improving error messages to distinguish between missing fields and oversized files.
Tech stack
javascriptnodejsexpress
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Needs investigation
Prerequisites
Node.jsMulter
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20