Question

Having issues uploading images using pre-signed POST URLs

I’m trying to upload an image using a pre-signed POST URL but it fails somewhat randomly.

Sometimes it returns the correct 204 code, but in roughly 50% of cases it returns 400 with a message:

<?xml version="1.0" encoding="UTF-8"?><Error><Code>InvalidArgument</Code><Message>Malformed JSON</Message><BucketName>XXXXXX</BucketName><RequestId>tx00000f65f55d800802749-00658c2492-d1de9a73-fra1b</RequestId><HostId>d1de9a73-fra1b-fra1-zg02</HostId></Error>

I’ve tried different boto3 and requests package versions but to no avail.

The issue started to appear on 24th December and is still occurring.

Here is the test code:

import requests

import requests
from botocore.exceptions import ClientError
import boto3


AWS_S3_ENDPOINT_URL = f"https://fra1.digitaloceanspaces.com"
do_spaces_client = boto3.client(
    "s3",
    aws_access_key_id="XXXXXXXXXXX",
    aws_secret_access_key="XXXXXXX",
    region_name="fra1",
    endpoint_url=AWS_S3_ENDPOINT_URL,
)

def create_presigned_post(
    bucket_name, key, fields=None, conditions=None, expiration=10 * 60
):
    try:
        response = do_spaces_client.generate_presigned_post(
            bucket_name,
            key,
            Fields=fields,
            Conditions=conditions,
            ExpiresIn=expiration,
        )
    except ClientError as e:
        print(e)
        return None

    return response

def upload_image_to_s3(
    s3_obj_name: str,
    img_bytes: bytes,
    presigned_url: str,
    presigned_fields,
    timeout: int = 180,
) -> int:
    files = {"file": (s3_obj_name, img_bytes)}

    resp = requests.post(
        presigned_url,
        data=presigned_fields,
        files=files,
        timeout=timeout,

    )
    print(resp.text)
    resp.raise_for_status()

    return resp.status_code

resp = create_presigned_post(bucket_name="XXXXX", 
                             key="test_image.jpg",
                fields={"Content-Type": f"image/jpeg"},
                conditions=[{"Content-Type": f"image/jpeg"}],
                             )
upload_image_to_s3(s3_obj_name="test_image_8.jpg", img_bytes=b"fejifejfejofe", 
                   presigned_url=resp['url'], presigned_fields=resp['fields'])

Submit an answer


This textbox defaults to using Markdown to format your answer.

You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!

Sign In or Sign Up to Answer

These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.

I’m experiencing the same issue, also starting roughly in the time range you mentioned. Pre-signed POST requests to Spaces from browsers fail sporadically, and I don’t see any malformed request data when trying to reproduce this issue.

I just submitted a support ticket for this issue (#08501990).

have the same issue, any prgoress with the support ticket?

It suddenly started appearing for us on an existing bucket too.

Try DigitalOcean for free

Click below to sign up and get $200 of credit to try our products over 60 days!

Sign up

Get our biweekly newsletter

Sign up for Infrastructure as a Newsletter.

Hollie's Hub for Good

Working on improving health and education, reducing inequality, and spurring economic growth? We'd like to help.

Become a contributor

Get paid to write technical tutorials and select a tech-focused charity to receive a matching donation.

Welcome to the developer cloud

DigitalOcean makes it simple to launch in the cloud and scale up as you grow — whether you're running one virtual machine or ten thousand.

Learn more
DigitalOcean Cloud Control Panel