R4 APIs (Millennium)

Hello,

I'm trying to update the DocumentReference but getting the 409-Conflict error. Can you please assist in resolving the issue?

Thanks!

Content-Type: application/fhir+json
Accept: application/fhir+json
Authorization: Bearer <valid token with document.write scope>
If-Match: W/"2"

X-Request-Id: 2d351283-88a4-b550-c4c7-6a16f7e7fa67+ZB6S_RyjJ

{
    "resourceType": "OperationOutcome",
    "issue": [
        {
            "severity": "error",
            "code": "conflict",
            "details": {
                "text": "Current state of resource in conflict"
            }
        }
    ]
}