Shape 5

I have begun having an issue with Internet Explorer 11 browsers and the WordPress plugin "PDF Embedder", not working.  I am getting the following error message when I load a page that uses PDF Embedder, "Unable to get property 'isStreamingSupported' of undefined or null reference".  This error does not occur when using Firefox 57.0.4 or with the Safari browser on IOS devices with IOS 11.2.2 or 10.3.2.

So why ask Shape5?  My site has been a longtime user of the Shape5 for WordPress Vertex Free theme.  If I change my websites theme to the WordPress Twenty Seventeen theme, the issue with PDF Embedder plugin and Internet Explorer 11 is non existent.  I would prefer to continue working with my Shape5 Vertex theme.

A little background:
I first noticed this issue after moving my website from old web host to new web host.  Yes, the new web host is using newer version 7.0 of PHP and most other parts are a little more up to date also.  The website was running WordPress 4.8.5 and Vertex Free for WP 4.0.  As I was testing the website after the web host move, I found this issue.  I personally use Firefox as my default browser and have not made a habit in recent months of testing web pages with Internet Explorer, therefore I am not exactly sure when this issue surfaced.

My further testing involved creating the following new page: http://devwp.redhedoil.com/2018/01/test-pdf-embedder-new-post-new-pdf/ (http://devwp.redhedoil.com/2018/01/test-pdf-embedder-new-post-new-pdf/) to see if the issue was with existing pages only.  No change.

I deleted the PDF Embedder plugin and reinstalled.  No change.

I updated Vertex Free for WP from 4.0 to 4.1.  No change.

I updated Wordpress from 4.8.5 to 4.9.2.  No change.

Support for PDF Embedder plugin suggested the following:
"I would recommend updating the theme if possible. The theme developer may also be able to assist with any JS within their theme that is breaking plugin functionality. Unfortunately, IE browsers are still ridiculously quirky and any broken JS can cause a cascading failure with other JS elements.

I'm not familiar with the Vertex Theme but if it uses any sort of AJAX to load the pages, this might the source of the issue. If that is the case, the 2nd piece of code in the following documentation may resolve the issue for you: https://wp-pdf.com/kb/the-viewer-doesnt-display-at-all-or-at-wrong-size-when-inside-a-javascript-based-tab-or-ajax-page-transitions/ (https://wp-pdf.com/kb/the-viewer-doesnt-display-at-all-or-at-wrong-size-when-inside-a-javascript-based-tab-or-ajax-page-transitions/)"

I am not competent at a code level to delve into this further, therefore I am asking for help with this.  Our use of PDF Embedder (or a functional equivalent) is paramount to a portion of our website.

Kindest Regards,
Alex Fassas

Vertex does not use any AJAX on the front end.  Is there a reason that you need to still support IE 11?  Most of the internet no longer supports any version of IE, as Edge was released a while ago, and the majority of people use Chrome or Firefox.

If you find that you still have an occasional user on outdated software, there are multiple plugins for WordPress that prompt people to update their browser.  It may be worth considering a message along the lines of "Portions of this site can only be viewed in a modern browser, please consider updating." in order to prompt your visitors to use a more secure option.

A quick search found this plugin, but I'm sure there are a lot of other options, if this one isn't what you want: https://en-za.wordpress.org/plugins/wp-browser-update/

Tristen,

Thank you for the response.  My day job work environment is still working very nicely in the MS Windows 7 Pro world with IE 11 browsers.  Personally I am a Firefox fan and that is what I use.  When working on the website publishing, I am only checking what I know, which of course includes IE 11.  Apparently I have been under a rock, as I have no idea about MS Edge.

I will take a look at our website analytics and see what browsers are in use to our site and go from there.  My guess is that IE 11 is still holding a big piece of the browser clients, except for newer hardware which has the latest and greatest already installed.

Thanks again,
Alex