Migrating from legacy: SharePoint Classic and Add-ins

SharePoint Add-ins

Add-ins are an old technology. They were only around for a few years, and thankfully are not widely used. In November 2023, the deprecation of these apps was announced. In 2026, they’ll stop working entirely.

You’ll see this warning in your SharePoint app catalog:

App catalog add-in retirement warning

The Add-in technology has been replaced by SharePoint Framework since 2016. This a modern, mature development environment which provides for a much better user experience.

In the words of Microsoft:

Is SharePoint Framework (SPFx) impacted by these retirements? No, SharePoint Framework (SPFx) is the recommended development model for SharePoint extensibility and is not impacted by these retirements. These retirements only affect SharePoint Add-Ins (a legacy development model) and Azure ACS (a legacy auth model). (source):

If you are using Add-ins today, you’ll need to contact the software vendor for a migration path.

None of our applications are implemented as Add-ins, and are instead build on the modern SharePoint Framework (SPFx). This is in line with Microsoft roadmap and will be fully supported for many years to come.

SharePoint Classic vs Modern

Classic sites are the original SharePoint style. Here’s a classic and modern comparison:

Modern sites are more visually appealing, have better usability, and more importantly, the performance is significantly improved - especially with 3rd party apps and integrations which are now seamlessly included in the page instead of relying on iframes and other “hacks”.

The modern pages are responsive - meaning they’ll work on any screen size. Lists are way more powerful, allowing you to set up custom views much more easily, and search the list.

In short, modern is the future.

However, classic had a lot of things people loved - there were a bunch of web parts included such as for search, calendar, links and so on. There used to be a classic list “Gantt view” which hasn’t been brought to modern - primarily, we believe, because Microsoft want to encourage an upgrade to Planner Premium. This is why we introduced our Gantt app for SharePoint Modern.

Custom Scripts

Custom Scripts was a feature that powered many Classic features. It allowed the execution of custom JavaScript within the page to control custom features. For example, a lot of classic web parts required it: Content Rollup web parts, Embed, Content Editor/Script Editor, search web parts, social web parts…the list goes on. Custom Scripts turns itself off every day and has to be re-enabled by an administrator. Some time in 2026, it’ll be disabled entirely. We believe this will accelerate the migration to Modern.

When is the SharePoint Classic end of life?

This hasn’t been announced. Instead, Microsoft have taken the approach of deprecating and end-of-lifing individual features within Classic, to nudge (and often shove) administrators and end users towards the modern experience.

Summary

It’s time to do two things: move from classic to modern sites, and replace your Add-ins.

Of course, all our apps are compatible with the modern experience and don’t use Add-in technology. Have a look at our solutions and get in touch if you have questions. Thanks for reading.