December 14, 2026. That’s the date Umbraco 13 LTS reaches end of life.
As of April 17, that gives you 241 days. Sounds comfortable, until you actually map it out:
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30 days disappear into the year-end holiday freeze
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Weeks go into approvals and discovery
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Time to properly learn the Bellissima backoffice (not skim it, actually work with it)
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Time to figure out where AI fits into your workflow
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Time to plan content properly with Umbraco 18’s Element Library in mind
Once you break it down like this, those 241 days feel a lot shorter. More like a working window than a long runway.
(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.)
Bellissima: Why This One Actually Matters
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.
Don’t Port It. Rethink It.(Future)
A common pattern we see: teams rebuild their existing dashboards in the new stack. Same experience, just with newer tooling.
That feels safe, but it brings all the old decisions with it.
Before touching v17, take a proper pass through v13:
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Property editors that are no longer used
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Dashboards that nobody has opened in months
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Custom pieces that made sense at the time
If something doesn’t have a strong reason to exist, leave it behind. And for the pieces you keep, rebuild them properly instead of translating them line by line.
Port-and-patch tends to come back and bite within a few months.
Two small things worth noting early:
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Smidge was removed in v17 and needs to be added separately
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Umbraco Forms has moved to an annual license
The .NET 10 Bit (Worth Paying Attention To)
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
This part is easy to dismiss, but it shouldn’t be.
Umbraco 13 was built for a person working in the backoffice. Umbraco 17 opens the door for people and tools working together.
With the Management API, content can be read, updated, and used as context by external tools. The Umbraco MCP Server takes that further by letting AI tools interact directly with the backoffice.
That changes how content workflows can work in practice.
If AI is even a small part of what you’re planning, this becomes an important factor.
One More Thing: Umbraco 18 and the Element Library
By the time December comes around, Umbraco 18 will likely be part of your planning.
The Element Library is the headline feature. It allows you to take a content block, promote it to a shared library, and reuse it across pages. Update it once, and the changes apply wherever it’s used, with visibility before publishing.
It solves the copy-paste problem that every content team runs into at some point.
Why this matters now: it builds on the same Bellissima architecture introduced in v17. If you structure content with reusable components during your upgrade, moving into this later becomes straightforward.
If not, you’ll be revisiting the structure again sooner than you’d like.
Check out the future: You can watch the early concepts of the Element Library in action here: Early concepts for Reuse Content of Blocks.
The Bottom Line
241 days is enough time to do this properly.
It’s also short enough that rework becomes expensive.
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.
If you are planning an Umbraco 13 to 17 upgrade and want a second opinion on architecture, packages, or editor experience, we are happy to review your current build and talk through the path with you. As an Umbraco Contributing Gold Partner, we help teams upgrade with less rework and a better view of what comes next.