OpenSeadragon not able to load images giving 403/500 error

Question

I am trying to migrate my code from seadragon 0.8.9 to Openseadragon 2.4.1 I am trying to add functionalities to the image viewer like adding rotation buttons, which I am able to. Here is the seadragon code:

    viewer = new Seadragon.Viewer('container');

    viewer.addEventListener('open', addHighlight);

    if(openListener != undefined && openListener != null) {
        viewer.addEventListener('open', openListener);
    }

    var nav = viewer.getNavControl();

    viewer.clearControls();

    viewer.addControl(nav, Seadragon.ControlAnchor.TOP_LEFT);

    viewer.openDzi(imagePath, imageViewerXml);

And here's the openseadragon code:

    viewer = new OpenSeadragon.Viewer('container');

    viewer.addHandler('open', addHighlight);

    if (openListener != undefined && openListener != null) {
        viewer.addHandler('open', openListener);
    }

    var navbar = document.createElement("div");

    viewer.addControl(navbar, { anchor: OpenSeadragon.ControlAnchor.TOP_LEFT });

    viewer.open(imagePath, imageViewerXml);

where in both the code imagePath is the 'tileSources' and imageViewerXml is 'initialPage' as described in Openseadragon .js file.

I am getting Error in loading the .dzi file on my QA environment. What am I doing wrong. Please help!! Thanks in Advance!!!