Wrong response code from failed precondition If-None-Match

[bbraatCrwd]

Describe the bug

When submitting a write to an object in S3 with the If-None-Match header set in the SDK, a 200 response code can occasionally be returned along with the expected Exception, rather than the expected 412 response code.

Regression Issue

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

Expected Behavior

I expect to see a 412 response code every time this pre-condition is not met. The flakiness of the response code makes handling the return more cumbersome.

Current Behavior

This is a possible Exception/response payload that can be returned on failing the pre-condition:
software.amazon.awssdk.services.s3.model.S3Exception: At least one of the pre-conditions you specified did not hold (Service: S3, Status Code: 200, Request ID: 9YD49V2HRSDRS8K1, Extended Request ID: jUpbn2VaLT6Kwi6vyaN32y1OOWX0ShIocGfV+9+I7qG7kmmAR7kVCA3WATwcjpDMPdTEg3hLPuI=)

Reproduction Steps

The issue happens intermittently on the S3 side and it is not clear how to reproduce.

Possible Solution

No response

Additional Information/Context

No response

AWS Java SDK version used

2.29.1

JDK version used

24

Operating System and version

Multiple environments

[debora-ito]

Reproduction Steps
The issue happens intermittently on the S3 side and it is not clear how to reproduce.

Understood. Can you provide a code snippet showing the s3 client and the GetObject request call, so I can try to reproduce the same conditions?

[steveloughran]

so it is an exception being triggered -but the status code is 200?

odd

[bbraatCrwd]

Reproduction Steps
The issue happens intermittently on the S3 side and it is not clear how to reproduce.

Understood. Can you provide a code snippet showing the s3 client and the GetObject request call, so I can try to reproduce the same conditions?

This is on upload, not download. The example I was looking at was on a multipart upload during one of the upload part calls:
val uploadPartRequest = UploadPartRequest.builder() .bucket(bucket) .key(key) .uploadId(uploadId) .partNumber(partNumber) .contentMD5(chunkMd5) .contentLength(chunk.length) val body = AsyncRequestBody.fromBytesUnsafe(chunk) client.uploadPart(uploadPartRequest.build(), body)

[bbraatCrwd]

so it is an exception being triggered -but the status code is 200?

odd

That is correct, we receive it like any other exception, but the status code is a 200 instead of the expected 412

[debora-ito]

@bbraatCrwd sorry, you're right, if-none-match makes no sense with read operations.

I'm wondering if this is a s3 server-side issue - the SDK usually don't modify a response status code, according to the exception you pasted it looks like the 200 was sent by s3, the SDK is only unmarshalling the response. Maybe some edge case of what is described in the multipart upload scenario here.

One way to confirm this is to generate the verbose wirelogs and get the actual response at the error moment (instructions for the verbose wirelogs can be found in our Dev Guide); the other is to reach out to the s3 team with your request ID (you'll need to provide a more recent one) and ask them to investigate. Let us know what you think.