---
title: "S3 Conditional Writes"
slug: "s3-conditional-writes"
tags: ["5.4"]
updated: 2026-10-28T01:54:03Z
published: 2026-10-28T01:54:03Z
canonical: "docs.vastdata.com/s3-conditional-writes"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vastdata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# S3 Conditional Writes

VAST Cluster supports [S3 conditional writes](https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3-conditional-writes/). If a PutObject or CompleteMultipartUpload request contains the `If-None-Match` header and the value is '*', the object is uploaded only if there is no existing object with the same key name in the bucket.

Conditional writes are not supported for versioned buckets.