We believe a recent upgrade to Windows and/or Edge has caused a change in behavior when downloading web pages. When a page/tab contains a pdf file the html page source text gets downloaded and not the pdf file. Nothing appears too have changed with the presentation of the file. We read it fine.
What could cause this?
The pdf file is sent to the client from the server with the following content headers: (don't remember why cache-control is set to private)
$this->response->setHeader('Cache-Control', 'private');
$this->response->setHeader('Content-type', 'application/pdf');