How to capture image from camera and convert the image to base 64 string send to the server in xamarin forms? - xamarin.forms

Question

I am new to xamarin forms. I implement a simple program where the image is capture from the camera and convert into base64 string and send it to the server like below.
private async void AddNewPhoto(object sender, EventArgs e)
{
MemoryStream memoryStream = new MemoryStream();
img.Source = ImageSource.FromStream(() =>
{
var stream = file.GetStream();
file.GetStream().CopyTo(memoryStream);
return stream;
});
paths.Enqueue(filePath);
imgPaths.Add(file);
val.Add(img.Source);
// Set StackLayout in XAML to the class field
parent = headerStack1;
parent.Children.Add(img);
}
async void btnSubmitClicked(object sender, EventArgs args)
{
if (paths.Count > 0)
{
string URL1 = "";
string basicDomain1 = AppConstant.ComplaintsUploadImageURL + PhoneNo + "~secretcode-" +
secretCode;
MultipartFormDataContent form1 = new MultipartFormDataContent();
DependencyService.Get<IHudService>().ShowHud("Loading");
List<string> pathItems = new List<string>();
for each (MediaFile ph in imgPaths)
{
var fileName = filePath.Split('\\').LastOrDefault().Split('/').LastOrDefault();
var file = ph;
var upfilebytes = File.ReadAllBytes(file.Path);
var base64 = Convert.ToBase64String(upfilebytes);
var content = new StringContent(base64);
form1.Add(content, "image_64string");
Dictionary<string, string> UploadJson = new Dictionary<string, string>();
UploadJson.Add("image_txt", imgText);
form1.Add(new StringContent(UploadJson["image_txt"]), "image_txt");
form1.Add(new StringContent("jpg"), "image_extension");
var response_ = await this.apiService.PostImageRequest(form1, URL1, basicDomain1);
if (!response_.IsSuccess)
{
await Application.Current.MainPage.DisplayAlert("Error", response_.Message, "Network Problem!!");
return;
}
}
}
}
But it shows the error "Can not access the closed stream." How to fix this error?