X-Amz-Request-Id
The HTTP X-Amz-Request-Id response header is an unofficial, AWS-specific header containing a unique identifier assigned by Amazon S3 to every request.
Usage
Amazon S3 generates a unique request ID for each incoming request and returns the value in the X-Amz-Request-Id header. This identifier serves as the primary reference when tracing requests through AWS infrastructure or when opening AWS support cases.
The value is a short uppercase alphanumeric string, typically 16 characters. Each request produces a different ID regardless of whether the request succeeds or fails. S3 logs this value internally, making the header essential for correlating client-side observations with server-side records.
AWS support requires both X-Amz-Request-Id and X-Amz-Id-2 when investigating S3 issues. The two headers together uniquely identify the request and the host processing the request. Logging both values on the client side speeds up troubleshooting.
The header is similar in purpose to X-Request-Id, which serves the same role in non-AWS environments.
Note
The "X-" naming convention for HTTP headers, "X" referring to "experimental", has been deprecated and needs to be transitioned to the formal naming convention for HTTP headers.
Values
Request identifier string
The value is a short uppercase alphanumeric string assigned by S3. The length is typically 16 characters. The string has no documented internal structure and is unique per request.
Example
Every S3 response includes a request ID. The value is a short uppercase string used as a lookup key in AWS support and internal logging systems.
X-Amz-Request-Id: ZFQ6A0RQV9FWMYZM
Different requests to the same bucket or object produce distinct identifiers.
X-Amz-Request-Id: W4PC6J5M48TMP3CA
A typical S3 response includes the request ID alongside the extended request identifier and other AWS-specific HTTP headers. Both request identifiers are needed when contacting AWS support.
X-Amz-Request-Id: TV9A5STHP2EB68KX
X-Amz-Id-2: Rd+VkxLchOwmgK/K8Q+kzOuevaVu7BF+Vwfeul+L89DNQX8xDhsYo9W+U/EwI0svlSXb4XtyNVU=
X-Amz-Server-Side-Encryption: AES256
Content-Type: text/plain
Takeaway
The X-Amz-Request-Id header provides a unique request identifier assigned by Amazon S3, used alongside X-Amz-Id-2 for log correlation and AWS support case resolution.