> ## Documentation Index
> Fetch the complete documentation index at: https://gcore-doc-1894.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Traceparent header for troubleshooting

Every response that passes through the Gcore CDN includes a `traceparent` header — a unique identifier for that request. Copy it and send it to [Gcore Support](mailto:support@gcore.com) when opening a troubleshooting case so Support can pinpoint the exact request in Gcore systems.

`traceparent` follows the [W3C Trace Context specification](https://www.w3.org/TR/trace-context/). The header carries a `trace-id` (identifies the whole trace) and a `parent-id` (identifies the CDN span). The CDN keeps `trace-id` unchanged as the request moves from client to origin, and updates `parent-id` to represent its own operation. If the client omits the header or sends an invalid value, the CDN generates a conforming one.

<Info>
  Gcore CDN also forwards the `tracestate` request header from the same specification, without modifying it.
</Info>

## Read the traceparent header

Read the response header in browser developer tools (Chrome DevTools) or with curl. This command makes a normal GET request and prints only the response headers:

```curl theme={null}
curl -sS -D - -o /dev/null https://cdn.example.com/path/to/file
```

<Frame>
  <img src="https://mintcdn.com/gcore-doc-1894/tz93sQyLuauBxlSr/images/docs/cdn/troubleshooting/traceparent-header-for-troubleshooting/traceparent-devtools.png?fit=max&auto=format&n=tz93sQyLuauBxlSr&q=85&s=6157546c9792a3d549ba766f8c0c827b" alt="traceparent header in Chrome DevTools" width="1174" height="666" data-path="images/docs/cdn/troubleshooting/traceparent-header-for-troubleshooting/traceparent-devtools.png" />
</Frame>

<Frame>
  <img src="https://mintcdn.com/gcore-doc-1894/tz93sQyLuauBxlSr/images/docs/cdn/troubleshooting/traceparent-header-for-troubleshooting/traceparent-curl.png?fit=max&auto=format&n=tz93sQyLuauBxlSr&q=85&s=43962ba5b19af0738a6607eb3fbf8034" alt="traceparent header in a curl response" width="1104" height="709" data-path="images/docs/cdn/troubleshooting/traceparent-header-for-troubleshooting/traceparent-curl.png" />
</Frame>

If the origin or application already records W3C Trace Context, match the same `trace-id` in those logs to correlate the request end-to-end.

## Traceparent in Raw logs

[Raw logs](/cdn/logs/raw-logs-export-cdn-resource-logs-to-your-storage) include the `$http_traceparent` field. That field stores the `traceparent` header from the incoming client request — the value the CDN received. It is not the rewritten header forwarded to the origin, and it is not the `traceparent` returned in the CDN response.

If the client omits the header, `$http_traceparent` contains `-`. If the client sends an invalid value, the field contains that original invalid value, while the CDN generates a valid replacement for the request to the origin.

A sample value looks like this:

```
00-d5fe1dc9035165ce36952daf29686b6c-14330be33197dd1a-01
```

In this example, `d5fe1dc9035165ce36952daf29686b6c` is the 16-byte `trace-id`, and `14330be33197dd1a` is the 8-byte `parent-id` from the client's request. The `trace-id` stays the same for the whole request, so it can be matched to origin or APM traces that follow W3C Trace Context. The `parent-id` in `$http_traceparent` is the caller's ID as received from the client. The CDN-generated `parent-id` that the origin records as its parent span ID is in the header forwarded to the origin, not in this log field.