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 15^th 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:

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.