C#

int row_idx = 1;
ConcurrentBag<(int, string, float)> bag = new ConcurrentBag<(int, string, float)>();
Parallel.ForEach(elements, element =>
{

    string fname = element.name;
    float ftrack = (float)(element.track);


    var elementsToAdd = new (int, string, float)[]
    {
        (row_idx, fname, fsize)
    };

    bag.Add(elementsToAdd[0]);

    row_idx++;

    ProgressBar1.Text = fname; // <<---- error here
    ProgressBar1.Update();
    //Application.DoEvents();

});