To get the dashboard and left panel working I had to modify the following code....
added this line $this->template = strval(str_replace("\0", "", $this->template));

Is this a bug?

Problem in concrete5-8.4.0RC4 and concrete5-8.3.2 code.

public function renderViewContents($scopeItems)
{
$contents = '';

// Render the main view file
if ($this->innerContentFile) {
$contents = $this->renderInnerContents($scopeItems);
}

// Render the template around it
$this->template = strval(str_replace("\0", "", $this->template));

if (file_exists($this->template)) {
$contents = $this->renderTemplate($scopeItems, $contents);
}

return $contents;
}

"concrete/src/View/View.php"