Netlify Forms sometimes returns 408 or 502 (x-nf-request-id provided)

Hello support team,

we have a form connected with Netlify Forms and it works fine almost every time. We have found a use case that causes the form stop working: it happens when the user uploads specific files (they are just standard PDF, ~ 5MB weight, and I can open them up with preview app on my mac).

On this use case the server returns a 502 or 408 error immediately, without waiting the 10 seconds of the timeout. The error appears in less than 1 sec.
As soon as I change those PDFs with other PDFs, the form works as expected.

A sample request ID is:

x-nf-request-id: 01FY6N22NEM67N5ZQW2W57E525
x-nf-request-id: 01FY6P131A9J0S3H3ZF444GPHC

Our website is:
The form is in this url:
I also can send you the specifica PDF file that cause the form stop working. Just ask me with a DM.

Thank you.

hey there @Giulico ,

it seems like the acceptable file upload size may have changed, and we have not yet had a chance to update our documentation. Currently, the whole request body needs to be less than 8mb in total size, and it seems like everything over that limit causes problems.

We are going to update our docs, but in the mean time, we encourage you to make it clear to people using the form that the file size needs to be smaller than what it currently is.