Token refreshing C#

I'm catching an HttpRequestException using this

catch(HttpRequestException ex)
{
    Debug.WriteLine(ex.ToString());
}

trying to get acces using this

private async Task<List<string>> GetUpdateList(string dirPath)
        {
            List<string> list = new List<string>();
            var files = await dbx.Files.ListFolderAsync(dirPath);
            fileNames.Clear();

            foreach (var item in files.Entries.Where(i => i.IsFile))
            {
                fileNames.Add(item.Name);
                list.Add(item.Name[..^4]);
            }

            return list;
        }

And it logs

System.Net.Http.HttpRequestException: Response status code does not indicate success: 400 (Bad Request).
at System.Net.Http.HttpResponseMessage.EnsureSuccessStatusCode()
at Dropbox.Api.DropboxRequestHandler.RefreshAccessToken(String[] scopeList)
at Dropbox.Api.DropboxRequestHandler.CheckAndRefreshAccessToken()
at Dropbox.Api.DropboxRequestHandler.RequestJsonStringWithRetry(String host, String routeName, String auth, RouteStyle routeStyle, String requestArg, Stream body)
at Dropbox.Api.DropboxRequestHandler.Dropbox.Api.Stone.ITransport.SendRpcRequestAsync[TRequest,TResponse,TError](TRequest request, String host, String route, String auth, IEncoder`1 requestEncoder, IDecoder`1 responseDecoder, IDecoder`1 errorDecoder)
at MelisekGameManager.RWindow.GetUpdateList(String dirPath) in C:\Programming\C#\MelisekGameManager\MelisekGameManager\RWindow.cs:line 167
at MelisekGameManager.RWindow.gameSelect_SelectionChangeCommitted(Object sender, EventArgs e) in C:\Programming\C#\MelisekGameManager\MelisekGameManager\RWindow.cs:line 231