Umbraco 17 Upgrade Guide: What to Expect and How to Prepare

Umbraco 17 has officially entered its beta phase! The new long-term supported (LTS) version of the Umbraco CMS officially launches next month, on 27 November 2025, and it’s set to be one of the most significant updates yet. 

 Many organisations will be upgrading from Umbraco 13, the previous LTS version, which reaches end of life on 14 December 2026. That means if your site is currently running on Umbraco 13 or an earlier version, now is the time to plan your move and future-proof your platform. 

 At STM AGENCY, we’ve helped countless businesses navigate previous Umbraco upgrades, from long-term support (LTS) versions to short-term support (STS) releases. We know exactly where the pain points can appear. From managing legacy code and third-party integrations to minimising downtime and avoiding data loss, a well-planned upgrade can make the difference between a seamless transition and a costly disruption. 

In this article, we’ll explore what the upcoming Umbraco 17 LTS means, what’s new and exciting in Umbraco 17, and how to choose the right path, whether that’s upgrading your current site or rebuilding from new. 

Long-Term Supported Version of Umbraco 

Umbraco releases major versions roughly twice a year, with every fourth major release designated as a Long-Term Support (LTS) version. The next of these, Umbraco 17, officially launches on 27 November 2025, marking a big milestone for the platform and its community. For businesses running older or non-LTS versions, this release should be firmly on the radar. Once a version reaches its end of life, support and security updates stop - which means your site could be at risk of vulnerabilities, performance issues, or incompatibility with newer integrations. 

The LTS versions of Umbraco are designed to give teams confidence and stability, providing a longer support window and fewer disruptive upgrades. For businesses planning to maintain or grow their digital presence over the next three to five years, moving to an LTS release like Umbraco 17 is simply best practice. It’s a chance to stay secure, supported, and aligned with the latest .NET frameworks, ensuring your CMS can evolve with your business rather than hold it back. 

Why staying on an older version of Umbraco could hold you back 

If you’ve invested in Umbraco already, you’ll know the pain of support ending, of third-party packages lagging behind, or of customisations that make upgrades tricky. Staying on a legacy version might feel comfortable in the short term, but it quickly becomes costly and restrictive. Upgrading to a long-term supported (LTS) version like Umbraco 17 means fewer disruptive updates to manage, fewer breaking changes to navigate, and a much clearer, more predictable roadmap for maintenance. It’s about regaining control and ensuring your CMS remains an enabler for growth, not a technical burden slowing you down.  

The Benefits of Umbraco 17 

As the next Long-Term Supported (LTS) release, Umbraco 17 brings together stability, performance and innovation, giving businesses the confidence to grow without worrying about short-term fixes or costly rebuilds. An Umbraco 17 upgrade means faster performance, a cleaner architecture, improved workflows for editors and developers, and better alignment with modern .NET standards. In short, it’s an upgrade that doesn’t just protect your investment; it helps your website do more, last longer, and perform better.  

Stability + longevity 

Umbraco 17 is a Long-Term Supported (LTS) version, which means you’ll benefit from an extended support window — two years of support, plus one year of security updates. For businesses that rely on their website as a central part of their operations, this stability is invaluable. It allows for confident long-term planning, predictable maintenance schedules, and reduced risk of disruption. You won’t need to worry about short-term support cycles or compatibility issues, freeing up your team to focus on growth and innovation rather than firefighting technical debt. 

Future-proof your architecture 

While Umbraco 17 builds on the improvements introduced in versions 14 through 16, it represents a significant shift toward a modern, future-ready CMS. The platform is moving to a fully re-engineered back office UI, built using web components and Lit, which will make it faster, more flexible and more extensible. This modern architecture brings cleaner APIs, improved performance, and far greater opportunities for customisation, all while reducing reliance on legacy code. For developers, that means more efficient builds and fewer headaches maintaining older functionality.

For businesses, it means a site that can evolve easily alongside changing needs and technologies, staying competitive for longer without another rebuild looming on the horizon. 

Enhanced editor experience and developer tooling 

Every version of Umbraco brings refinements to the editor and developer experience, but version 17 is expected to take this a step further. Following the introduction of the new Rich Text Editor (Tiptap) and more flexible extension points in Umbraco 16, editors can expect a faster, more intuitive interface with a cleaner, more responsive design. Developers, meanwhile, will benefit from improved tooling and smoother upgrade paths, reducing the friction that often comes with managing content-heavy sites or rolling out new features. The result? A platform that works better for both content teams and developers, improving efficiency with enhanced editor workflows, reducing errors, and helping your marketing and tech teams collaborate more effectively.  

Better alignment with modern .NET and hosting environments 

Umbraco has been steadily modernising its foundation to stay in step with Microsoft’s .NET evolution, and version 17 cements that alignment. Running on the latest LTS version of .NET means better performance and support, stronger security and compatibility with the most up-to-date cloud and DevOps environments. For businesses that host with Azure or use containerised infrastructure, this alignment ensures a smoother, more reliable deployment pipeline and improved scalability. In essence, you’re setting your CMS up to integrate seamlessly with the modern digital ecosystem - not lag behind it. 

Reduced total cost of ownership 

There’s a cost in the migration or rebuild, but over time, staying on unsupported software introduces risk: higher maintenance costs, more break-fixes and potential downtime. By upgrading proactively to Umbraco 17, you reduce these hidden costs, improve efficiency and future-proof your site against major technical debt. A well-timed upgrade allows you to plan the transition properly, budget effectively, and avoid the chaos of a rushed rebuild when support finally ends. In our experience, businesses that plan their upgrades not only save money but also gain faster, more reliable websites that deliver a better experience for both users and internal teams. 

What are the options to upgrade to Umbraco 17? 

There are broadly two paths to Umbraco 17: (a) an upgrade path (migrate your existing site) or (b) a full rebuild on Umbraco 17. We’ll walk through each of the technical considerations, the common challenges and at the end help you choose the right path.  

a) Upgrade path (incremental migration)

What this means 

You take your existing site (let’s say you’re currently on Umbraco 15 or 16) and you follow a sequence of upgrades until you land on Umbraco 17 - preserving your content, templates, customisations, integrations, etc. 

Technical considerations & challenges 

• Customisations and legacy code: If your site has extensive custom code (property editors, dashboards, packages, back-office extensions), then the upgrade path can be complex. For example, if you’re moving from older versions of Umbraco and those extensions rely on old APIs, you’ll need to refactor. 

• Breaking changes: Major versions often include breaking changes; the upgrade documentation must be followed closely. 

• Third-party packages: Some packages may not support the newer version or may require licensing updates. You’ll need to audit dependencies. 

• Testing risk: Because you’re migrating a live site, you’ll want comprehensive QA (content, integrations, UX). You’ll need staging environments and rollback plans. 

• Performance/hosting changes: Upgrading may require targeting a newer .NET version or altering the hosting setup, so your ops/infra team must be ready. 

• Opportunity cost: While the upgrade is happening, your team may have limited bandwidth for new features. If you wait too long, you’re running on older tech while doing the upgrade. 

• Avoiding “version drift”: If you delay the upgrade or keep customisations from older versions, you might land in a situation where you’re on Umbraco 17 but carrying old tech debt. 

When this path makes sense 

• Your site architecture is clean, not overly customised or tangled with outdated packages. 

• The content model, templates and integrations are reasonably modern. 

• You want to preserve the current look/feel and functionality, and minimise business disruption. 

• Budget/time is moderate; you prefer evolutionary rather than revolutionary change. 

b) Full rebuild in Umbraco 17

What this means 

Rather than laboriously upgrade the old site, you take the opportunity to rebuild the site on Umbraco 17 from the ground up (or significantly refactor), perhaps consolidating legacy systems, streamlining templates, rethinking UX and building with the new version in mind. 

Technical considerations & challenges 

• Time & budget: A rebuild typically takes longer and costs more upfront. 

• Content migration: You’ll need to move or transform content from the old site to the new one; sometimes, re-thinking content models, taxonomy, etc. 

• Re-architecting integrations: If there are external systems (CRM, PIM, DAM, marketing automation), you’ll want to ensure they integrate cleanly with the new system and the new version’s APIs. 

• User-experience redesign: Since you’re rebuilding, you may want to revisit UX, accessibility, mobile-first, page speed, etc - this introduces project scope. 

• Training and adoption: Editors will see a new interface/back-office; change management becomes more significant. 

• Opportunity to modernise: On the flip side, you can remove legacy technical debt, obsolete code, outdated modules, and build something leaner, faster, and easier to maintain moving forward. 

• Future-proofing: A well-designed, fresh build on Umbraco 17 means you’ll be in a much stronger position for the next 3-5 years with fewer constraints. 

When this path makes sense 

• The current site is old, heavily customised, or the architecture has become brittle. 

• The business demands new functionality, a major UX redesign, or significant growth. 

• You see the website as a strategic asset and want to invest in a future-ready platform, not just a patch-up. 

• You’re willing to invest more upfront for a stronger foundation. 

Choosing the right path 

The short answer? It depends on your setup and the version you’re upgrading from. But here’s what you need to know. 

If your site is running on Umbraco 15 or 16, the move to version 17 should be relatively smooth. Most of the changes are incremental, meaning it’s more of an upgrade than a rebuild. Most database and schema migrations happen automatically when Umbraco 17 starts up, though larger or content-heavy sites should allow extra time for the process. Always back up, test thoroughly, and validate once complete. 

If you’re on Umbraco 13, this is considered an LTS-to-LTS upgrade, which does introduce a few more moving parts. While it’s not a full start-from-scratch rebuild, it does include the breaking changes introduced in Umbraco 14, so you’ll need to account for a little more development and testing along the way. Reviewing your custom code, integrations, and third-party packages early will help keep things on track. 

If you’re still using Umbraco 8 or below, upgrading to Umbraco 17 will require a complete rebuild. The platform’s move to the modern .NET 5+ framework in Umbraco 9 changed the core architecture, making a direct upgrade impossible. In short, the underlying technology is too different for a direct upgrade path. While that sounds daunting, it’s the perfect chance to modernise - removing legacy code, improving performance, and building a future-ready website. 

The main complexity lies in custom back-office extensions and third-party packages. The more bespoke your setup, the more testing and fine-tuning you’ll need. Umbraco provides clear documentation on deprecated features and compatible alternatives, so you’ll know exactly what to expect. 

Why Now is the Time for Those Big Changes 

When considering an upgrade or rebuild, it is also the perfect time to finally knock out the bigger site improvements that have been stuck on your to-do list. 

If you’ve recently been saying things like this in your meetings, then the scheduled upgrade gives us a cost-effective window to act: 

• "We really need to tidy up our site's content and structure." 

• "It's time to refresh the design or key brand elements." 

• "Our site feels slow, and performance is a growing concern." 

• "We'd like to add new features like payment gateways." 

• "We need to get serious about meeting accessibility standards." 

Final Thoughts: Plan your upgrade to Umbraco 17 early  

The countdown to Umbraco 17 is on. Whether you upgrade or rebuild, the decision you make now sets the tone for your website’s future: its stability, agility, supportability and cost-efficiency. Don’t let your site drift into unsupported territory with risk piling up. 

At STM AGENCY, we’re ready to guide you, map out the right path, execute with confidence, and ensure your Umbraco platform isn’t just “working” but is powering your business forward. 

If you’d like to talk through your current Umbraco version, explore what the upgrade would look like, or get an audit, get in touch - we’re here to help. 

We’ve seen the “pain points” many businesses face when they try to tackle an Umbraco upgrade themselves: missed dependencies, forgotten extensions, broken back-office workflows, content gaps, editor confusion, SEO hiccups. Our role is to minimise those risks and help you move forward confidently.