# ReceiveContentLengthHeader(ulong)

> Callback, invoked with a Content-Length header is received.

## Definition

* **Type:** Method
* **Namespace:** [UnityEngine.Networking](/engine/6000.6/script-reference/unityengine/networking.md)
* **Assembly:** UnityEngine.UnityWebRequestModule

```csharp
protected virtual void ReceiveContentLengthHeader(ulong contentLength)
```

### Parameters

**** (\[ulong]\(https\://learn.microsoft.com/dotnet/api/system.uint64)): The value of the received `Content-Length` header.

### Remarks

This callback is invoked on the main thread.

This callback is only called if a `Content-Length` header is received. If the remote server doesn't transmit a `Content-Length` header, but includes body data, then it's possible for [DownloadHandler.ReceiveData](/engine/6000.6/script-reference/unityengine/networking/downloadhandler/receivedata.md) to be invoked without receiving a call to this method.

This callback might be invoked more than once. For example, if a redirect is encountered that has a `Content-Length` header, followed by a standard response, which also has a `Content-Length` header, this method is invoked twice.