An Umbraco 13 to 17 upgrade starts with reviewing what your website needs to carry forward: backoffice customisations, packages, application architecture and editorial workflows.
Umbraco 13 reaches end of life on 14 December 2026. This article shares a developer’s perspective on the decisions to make before starting the upgrade.
Build your schedule around the work involved, including:
-
Your organisation’s deployment restrictions and holiday freezes
-
Weeks go into approvals and discovery
-
Time to properly learn the Bellissima backoffice (not skim it, actually work with it)
-
Time to figure out where AI fits into your workflow
-
Time to plan content properly with Umbraco 18’s Element Library in mind
Set the upgrade timetable around your approval process, development work, testing and deployment calendar.
(Not on v13 yet? From v8–9, the path is v10 → v13 → v17. From v10–12, get to the latest v13 first, then plan the jump. The timeline doesn’t change either way.)
The Bellissima Backoffice: What Changes from Umbraco 13
For years, extending Umbraco meant working inside AngularJS. It worked, but over time it started feeling out of step with how modern web development has evolved. Building custom property editors often felt harder than it should.
Bellissima changes that.
The backoffice in Umbraco 17 is built on Web Components and Lit. You’re working with modern TypeScript and browser standards. Your IDE finally does its job properly, autocomplete, refactoring, all the things you expect just work.
It sounds like a small improvement until you spend a full day in it. Then you realise how much effort the old approach was adding without you noticing.
If you’re using tools like Cursor or any AI-assisted editor, this becomes even more obvious. The code is more predictable, and that’s exactly what those tools need.
For a broader overview of the release, read our Umbraco 17 features and LTS support article.
Review Existing Customisations Before the Upgrade
.NET 10 Considerations for Your Umbraco 13 to 17 Upgrade
Moving to .NET 10 isn’t just a version bump.
One improvement editors will notice straight away is the rebuilt HybridCache. Restarts are faster, especially on larger sites. That reduces those awkward moments right after deployment when everything feels slower than it should.
There’s also support for load balancing the backoffice itself, not just the front-end. For setups that already run across multiple instances, this makes life easier.
There’s a sustainability angle as well. Faster responses mean less compute per request. It’s a small detail, but it adds up over time.
Why v13 Falls Short for AI Workflows
One More Thing: Umbraco 18 and the Element Library
The Bottom Line
Plan backwards from Umbraco 13’s end-of-life date on 14 December 2026. Leave enough time for architectural decisions, development, validation and deployment.
The teams in the best position by December are not the ones who waited the longest. They’re the ones who treated this as an architectural decision early on.
Start with an audit. Remove what no longer earns its place. Rebuild the rest with how content will be managed going forward in mind.The deadline is fixed. What you do with the time is still open.
Planning an Umbraco 13 to 17 upgrade? Explore Phases’ Umbraco upgrade services to discuss your current architecture, packages and editor experience, and establish the work your website needs.
