Question: I have a list in one file html called "filed1":

```
<ul> 
    <li>Nombre:<a class="boton" onclick=move() title="Caja">Caja</a><br> 
    <FONT SIZE=2>Fecha: 21/12/1994</font></font></li>
</ul>

```

Now I want to change a string in other html "filed2":

```
<a id="logo-header2">
    <h1>
        <span class="site-name" id="element">Details</span><br>
    </h1>
</a> 

```

Using Java Script:

```
function move() {
    mywindow = window.open("file2.html");
    mywindow.document.getElementById("element").innerHTML="Changed");
}

```

But there is an error which says that `mywindow.document.getElementById("element")` is NULL, why? The id element exists in the other window. Is there another way to change the string?

Answer: 
I just applied Update 1 to VS2015 Pro and am now getting the exact same error. It happens regardless of whether I make a new project or use my old 2015 Project. Looks like it's a bug in the update.
Not really a fix, but I went back to Visual Studio 2013, as it does not have this bug, and driver dev is working great.