Content-Type setting for downloading using dropbox api v2

There does not appear to be a need for a custom HTTP client in the sample code you have provided.  Is the custom HTTP client necessary, or can your code function without one?

The .NET SDK does not require a custom HTTP client in order to function, nor do you need to explicitly set the Content-Type header.  Our .NET SDK will automatically create an HTTP client and set the appropriate headers for each API.

I am able to run the following C# sample from our .NET tutorials page.  It assumes a file named "file.txt" in the root folder of your Dropbox account.

using System;
using System.Threading.Tasks;
using Dropbox.Api;

namespace sampleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var task = Task.Run((Func<Task>)Program.Run);
            task.Wait();
        }

        static async Task Run()
        {
            using (var dbx = new DropboxClient("<OAuth Token>"))
            {
                using (var response = await dbx.Files.DownloadAsync("/file.txt"))
                {
                    Console.WriteLine(await response.GetContentAsStringAsync());
                }
            }
        }
    }
}

If you are doing this on mobile, are you using a framework like Xamarin?

Hi

I am using Xamarin Forms.

I receive this error 

Error in call to API function "files/download": Bad HTTP "Content-Type" header: "application/x-www-form-urlencoded".
Expecting one of "text/plain", "text/plain; charset=utf-8", "application/octet-stream",
"application/octet-stream; charset=utf-8".

at this stage

 using (var response = await dbx.Files.DownloadAsync("/Test.PDF"))

That is the line of code I would expect to be throwing the error based on the information you've shared.

Your issue appears to be very similar to https://www.dropboxforum.com/t5/API-Support-Feedback/Xamarin-DropBox-APi-HTTP-400-Bad-request-on-DownloadAsync/m-p/302892.

Given that the code sample works in a standard .NET project, but does not in a Xamarin project, Xamarin is likely adding additional logic that is modifying the Content-Type header in this use case.  There is little we can do to help in this situation as we do not provide support for Xamarin issues with the official Dropbox .NET SDK.  One place to possibly find additional help could be the Xamarin forums.

thanks for the support 

will follow up with Xamarin

thanks again

Please post any issues with the Xamarin binding here: https://github.com/xamarin/xamarincomponents