$(document).ready(function() {
    if (typeof Sys !== "undefined") {
        var prm = Sys.WebForms.PageRequestManager.getInstance();
        prm.add_endRequest(Master_EndRequestHandler);
    }
});

function Master_EndRequestHandler(sender, args) {
    if (args.get_error() == undefined) {
    }
    else {
        var errorName = args.get_error().name + ":";
        var errorMessage = args.get_error().message;
        errorMessage = errorMessage.replace(errorName, "");
        errorMessage = errorMessage.replace("<br />", "\n");
        alert("An error occurred:\n" + jQuery.trim(errorMessage));
        args.set_errorHandled(true);
    }
}