Microsoft Office Add-Ins And Internet Explorer 11

As you may be aware from the global celebrations, Microsoft brought Internet Explorer 11 to the end of its life on June 15th 2022. Well, sort of. There are exceptions, and if you have an MS Office Add-In, Internet Explorer’s end-of-life is not necessarily its true end.

Why Are Add-Ins and Internet Explorer Linked?

Microsoft Office Add-Ins are actually web sites with access to a specific officejs Javascript library. They are registered with Office using a manifest XML file and executed inside a frame in Office. As an Add-In is a web site, it requires a web browser to run, and this is where it gets complicated.

The following table helps you understand which browser is used to run MS Office Add-Ins:

Operating SystemMS Office VersionBrowser
 Office On The WebWhatever browser you are running in
Windows 7+Office Standalone 2013 – 2019 (i.e. not Microsoft 365 subscription)Internet Explorer 11
Windows 10+Office Standalone 2021 (i.e. not Microsoft 365 subscription)Edge
Windows 7, 8, 10 (< v1903)Microsoft 365 SubscriptionInternet Explorer 11
Windows 10 (> v1903), 11Microsoft 365 Subscription < 16.0.11629Internet Explorer 11
Windows 10 (> v1903), 11Microsoft 365 Subscription >= 16.0.11629Edge

You can find the full table of browsers used by MS Office Add Ins on Microsoft’s page. However, from this snippet, you can see that, in some circumstances, Add-Ins use Internet Explorer to render.

Fortunately, at the same time that Microsoft end-of-lifed Internet Explorer 11, they also altered their AppSource (the app store for Microsoft Office Add-Ins) certification policies so that your Add-In no longer has to function with Internet Explorer for approval in the store. Microsoft asks (but does not require) that you at least get your Add-In to output a graceful failure message if it detects that it is running in Internet Explorer 11.

From a practical point of view, you should still consider supporting Internet Explorer 11. We typically still support this for our Add-Ins using a combination of shims, Babel and hand-coded workarounds. The reason for continuing to support it is that many users will still use off-the-shelf Microsoft Office rather than Microsoft 365 Office and so will see Add-Ins presented by Internet Explorer 11. We also recommend a graceful fallback approach where some features of your Add-In may not be available in Internet Explorer 11, even if the core functionality still works.

To read our previous update on MS Office Add-Ins and WOPI, please take a look at our blog. If you are interested in working with McKenna Consultants to create or maintain your Microsoft Office Add-In, please get in touch with our team today.

Nick McKenna
Since 2004, Nick McKenna, BSc, MBCS Biography has been the CEO of McKenna Consultants. McKenna Consultants is a bespoke software development based in North Yorkshire, specialising in Cloud development, mobile App development, progressive web App development, systems integration and the Internet of Things development. Nick also holds a First Class Degree in Computer Science (BSc) and wrote his first computer program at the age of nine, on a BBC Micro Model B computer. For the last 21 years, Nick has been a professional computer programmer and software architecture. Nick’s technical expertise includes; Net Core, C#, Microsoft Azure, Asp.Net, RESTful web services, eProcurement, Swift, iOS mobile development, Java, Android mobile development, C++, Internet Of Things and more. In addition, Nick is experienced in Agile coaching, training and consultancy, applying modern Agile management techniques to marketing and running McKenna Consultants, as well as the development of software for clients. Nick is a Certified Enterprise Coach (Scrum Alliance), SAFe Program Consultant (SAI), Certified LeSS Practitioner (LeSS) and Certified Scrum@Scale Practitioner. Outside the office, Nick is a professional scuba diver and he holds the rank of Black Belt 5th Dan in Karate.

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