AFNetworking上传图片到node.js失败了，node.js无法读取文件？

Question

我使用AFNetworking最新版本并尝试使用不同的方式上传图片：

    NSString *urlString = [baseUrlString stringByAppendingString:@"account/avatar"];

    NSDictionary *parameters = @{@"token": self.token};
    NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] multipartFormRequestWithMethod:@"POST" URLString:urlString parameters:parameters constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileURL:filePath name:@"file" fileName:@"filename.jpg" mimeType:@"image/jpeg" error:nil];
    } error:nil];


        [request setValue:self.token forHTTPHeaderField:@"token"];

    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];

    NSURLSessionUploadTask *uploadTask;
//    uploadTask = [manager
//                  uploadTaskWithStreamedRequest:request
//                  progress:nil completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
//                      if (error) {
//                          NSLog(@"Error: %@", error);
//                      } else {
//                          NSLog(@"%@ %@", response, responseObject);
//                      }
//                  }];
//    

    uploadTask = [manager uploadTaskWithRequest:request fromData:[NSData dataWithContentsOfURL:filePath] progress:nil completionHandler:^(NSURLResponse * _Nonnull response, id  _Nullable responseObject, NSError * _Nullable error) {
                              if (error) {
                                  NSLog(@"Error: %@", error);
                              } else {
                                  NSLog(@"%@ %@", response, responseObject);
                              }
    }];

    [uploadTask resume];

在node.js中，网页上传文件运行良好，但如果使用AFNetworking：

console.log(req.files);//print TypeError: Cannot read property of undefined