.net core 3.1 WebClient upload Could not find a part of the path error-CodePudding

I am trying to upload a file using the below code. But I am getting the error message Could not find a part of the path 'C:\source\repos\FTPTest\FTPTest\bin\Debug\netcoreapp3.1\ftp3.test.com\test123.txt'

static void ftpuploadtest()
        {
            String uriString = "ftp3.test.com/test123.txt";
            WebClient myWebClient = new WebClient();
            myWebClient.Credentials = new NetworkCredential("username", "password");
            string fileName = "C:\\Temp\\unitssstest.txt"; 
            byte[] responseArray = myWebClient.UploadFile(uriString, fileName);
            Console.WriteLine("\nResponse Received. The contents of the file uploaded are:\n{0}",
                System.Text.Encoding.ASCII.GetString(responseArray));
            
        }

Error

System.Net.WebException
  HResult=0x80070003
  Message=Could not find a part of the path 'C:\source\repos\FTPTest\FTPTest\bin\Debug\netcoreapp3.1\ftp3.test.com\test123.txt'.
  Source=System.Net.Requests
  StackTrace:
   at System.Net.FileWebRequest.CreateWriteStream()
   at System.Net.FileWebRequest.<>c.<BeginGetRequestStream>b__55_0(Object s)
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at System.Threading.Tasks.TaskToApm.End[TResult](IAsyncResult asyncResult)
   at System.Net.FileWebRequest.EndGetRequestStream(IAsyncResult asyncResult)
   at System.Net.FileWebRequest.GetRequestStream()
   at System.Net.WebClient.UploadBits(WebRequest request, Stream readStream, Byte[] buffer, Int32 chunkSize, Byte[] header, Byte[] footer)
   at System.Net.WebClient.UploadFile(Uri address, String method, String fileName)
   at System.Net.WebClient.UploadFile(String address, String fileName)
   at FTPTest.Program.ftpuploadtest() in C:\source\repos\FTPTest\FTPTest\Program.cs:line 20
   at FTPTest.Program.Main(String[] args) in C:\source\repos\FTPTest\FTPTest\Program.cs:line 11

  This exception was originally thrown at this call stack:
    [External Code]

Inner Exception 1:
DirectoryNotFoundException: Could not find a part of the path 'C:\source\repos\FTPTest\FTPTest\bin\Debug\netcoreapp3.1\ftp3.test.com\test123.txt'.

CodePudding user response：

Your URI string is being treated as relative and combined with the default BaseAddress (see Remarks on UploadFile)

Changing it to an absolute URI should resolve it (likely ftp://ftp3.test.com/test123.txt)