AnonymousAWSCredentials do not support this operation

[zlistiev]

Describe the bug

After upgrading AWSSDK.S3 to the latest version (3.7.415.13) it triggers exception "AnonymousAWSCredentials do not support this operation" when uploading to S3 bucket. Was fine at version 3.7.305.31.

var credentails = new AnonymousAWSCredentials();
_client = new AmazonS3ClientWrapper(new AmazonS3Client(credentails, region));

await _client.PutObjectAsync(new PutObjectRequest
{
				BucketName = bucketName,
				Key = s3Key,
				FilePath = file?.FilePath,
				CannedACL = somecannedacl
});

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

Object should be successfully uploaded using anonymous credentials

Current Behavior

PutObjectAsync throws "AnonymousAWSCredentials do not support this operation" exception when trying to upload object using anonymous credentials

Reproduction Steps

var credentails = new AnonymousAWSCredentials();
_client = new AmazonS3ClientWrapper(new AmazonS3Client(credentails, region));

await _client.PutObjectAsync(new PutObjectRequest
{
				BucketName = bucketName,
				Key = s3Key,
				FilePath = file?.FilePath,
				CannedACL = somecannedacl
});

Possible Solution

No response

Additional Information/Context

No response

AWS .NET SDK and/or Package version used

AWSSDK.S3 3.7.415.13

Targeted .NET Platform

.NET Framework 4.7.2

Operating System and version

Windows 11

[dscpinheiro]

The error message isn't great, but this is related to the S3 default integrity change we released a couple of months ago: #3610

The SDK now calculates checksums by default (and adds extra headers before sending the request to S3), but since you're using anonymous credentials the headers will be empty. I enabled debug logging and saw the actual error:

AmazonS3Client 35|2025-03-07T07:18:20.975Z|ERROR|Received error response: [<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>InvalidRequest</Code><Message>x-amz-sdk-checksum-algorithm specified, but no corresponding x-amz-checksum-* or x-amz-trailer headers were found.</Message><RequestId>KMXP5K03CD08YXRN</RequestId><HostId>13aJ8hoZl9ZnTITq4AEBfWJXo3bBurr4qcaIJjQAjXB+R7adO0ve9ztLScoceh57yF50k1GuejQ=</HostId></Error>]

We're taking a look, for a workaround you can set the RequestChecksumCalculation option in the AmazonS3Config to WHEN_REQUIRED.

[dscpinheiro]

Today's release (https://www.nuget.org/packages/AWSSDK.S3/3.7.415.14) includes a fix for this issue, I just tried the example again and it succeeded.

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