After upload file has been corrupted in rood directory

When i upload the file in root directory and then try to open but getting error-it's look like this we don't support this file format

Please do suggestion as per below code

public async Task UploadImage(UploadProgressArgs files)
{
var test = new ReturnInfo();
var outputDirectory = Path.Combine(Environment.CurrentDirectory, "TestFolder");
Directory.CreateDirectory(outputDirectory);
byte[] dataArray = new byte[files.Files.FirstOrDefault().Size];
var paths = Path.Combine(Environment.CurrentDirectory, "TestFolder", files.Files.FirstOrDefault().Name);
using (var stream = new FileStream(paths, FileMode.Create))
{
stream.Write(dataArray, 0, dataArray.Length);
}
}