I want to upload multiple files at the same time, is the purpose of the incoming parameters body, below is the code, when small file upload will be a problem, but a large file or multi-threaded upload will be an error, do you know what reason be cause?

 
//the client code 
Using (var stream=new FileStream (@ "e: \ \ upload test. PDF", FileMode. Open, FileAccess. Read)) 
{
Using (var client=new HttpClient ()) 
{
Using (var multiContent=new MultipartFormDataContent ()) 
{
Var bodyContent=new StringContent (Newtonsoft. Json. JsonConvert. SerializeObject (content), Encoding, UTF8); 
BodyContent. Headers. ContentDisposition=new ContentDispositionHeaderValue (" body "); 

Stream. The Position=0; 
Var streamContent=new streamContent (stream); 
StreamContent. Headers. ContentDisposition=new ContentDispositionHeaderValue (" attachment "); 

//upload body 
MultiContent. Add (bodyContent); 
//upload file stream 
MultiContent. Add (streamContent); 

Var. MultiResult=client PostAsync (url, multiContent). The Result; 
} 
} 
} 

 
//the server code 
[HttpPost] 
Public HttpResponseMessage Test () 
{
Var provider=new MultipartMemoryStreamProvider (); 
Task. Factory. StartNew (()=& gt; The provider=base. Request. Content. ReadAsMultipartAsync (). The Result, CancellationToken. None, TaskCreationOptions. LongRunning, TaskScheduler. (the Default). Wait (); 
Foreach (var item in the provider. Contents) 
{
//read the body parameter 
If (item. Headers. ContentDisposition. DispositionType=="body") 
{

} 
//read the file flow 
If (item. Headers. ContentDisposition. DispositionType=="attachment") 
{

} 
} 

Return new HttpResponseMessage (System.Net.HttpStatusCode.OK); 
}