BackgroundWorker - the calling thread cannot access the object

Question

So in my DoWork I have

List<KeyValuePair<String, BitmapImage>> Files = new List<KeyValuePair<string,BitmapImage>>((List<KeyValuePair<String, BitmapImage>>)e.Argument);

foreach (KeyValuePair<String, BitmapImage> i in Files)
{
    string temp = i.ToString();               .......(1)
    //.....
}

I pass the argument as follows: -

backgroundWorkerForReupload.RunWorkerAsync(files);

where "files" are of type List<KeyValuePair<string, BitmapImage>>

In line (1) above, he displays a message InvalidOperationExceptionwith the message: "The calling thread cannot access this object because it has a different thread."

I am confused why it ibelongs to another thread. Any help would be greatly appreciated. Thanks.

Answer 1

WPF, BitmapImage, - , .

BitmapImage, Freeze().