Umbraco v13 vs v17: Why now is the time to upgrade and how to do it right

With Umbraco v13 reaching end of life this December 2026, organisations running business‑critical websites face an important decision: delay and risk disruption, or act now and upgrade on your own terms.

While upgrading CMS platforms is never just a box‑ticking exercise, the move from Umbraco v13 to v17 is more than a routine version change. It marks a clear shift in Umbraco’s architecture, performance model and editorial experience. Done correctly, it’s an opportunity to modernise rather than simply “keep up”.

This is where planning makes the difference.

What Staying on Umbraco v13 Really Means

Once Umbraco v13 reaches end of life, sites running on it will no longer receive:

• Security patches

• Bug fixes

• Platform support

For many organisations, this introduces unnecessary risk, particularly for those sites that underpin communications, lead generation or service delivery.

More importantly, upgrading under time pressure increases the likelihood of rushed decisions, technical debt and avoidable downtime. The safest upgrades are planned, phased and deliberate, not reactive.

Umbraco v17: A Step Change, Not a Small Increment

Comparing Umbraco v13 and v17 isn’t simply a matter of “what’s new”. v17 represents a structural evolution of the platform.

A modern backoffice architecture

Umbraco v17 introduces the Bellissima backoffice, replacing AngularJS with modern Lit web components. This fundamentally changes how custom backoffice extensions, dashboards and tools are built.

For organisations with bespoke editors or custom workflows, this means:

• Legacy extensions must be rewritten using the new extension API

• TypeScript becomes the standard, improving stability and maintainability

• Backoffice development is significantly more future‑proof

It’s a cleaner foundation but one that requires preparation.

Improved Performance and Scalability

v17 also introduces Hybrid Cache, allowing route‑based caching, pre‑seeded content and optional offloading to Redis or SQL. For content‑heavy or high‑traffic sites, this delivers tangible performance improvements without compromising flexibility.

A Better Editorial Experience

Editors benefit from:

• Cleaner list views using Label Templates

• More structured, modern content approaches

• A backoffice designed for long‑term usability, not legacy constraints

This isn’t just a developer upgrade. It directly impacts day‑to‑day content teams.

AI Built into Umbraco v17, Not Bolted On

One of the most meaningful differences between Umbraco v13 and Umbraco v17 isn’t performance, support lifecycle, or cloud readiness. From v17 onwards, AI can become a practical part of how content is created and managed inside Umbraco.

Umbraco AI provides the foundation, but out of the box it has limitations. At ClerksWell, our Umbraco MVP Tech Lead Paul Seal has extended it with bespoke tooling that embeds AI directly into the editorial workflow.

In the demo below, you’ll see this in action. From a single prompt, the system generates a complete, publish‑ready blog article. It creates structured content, populates the correct blocks, selects supporting imagery and publishes the page automatically, all in under 30 seconds. This is AI as part of the CMS, not a bolt‑on or a copy‑paste exercise.

Using custom Umbraco AI tools to write a whole article automatically 

This level of AI integration simply isn’t realistic on Umbraco 13. While v13 can be extended, Umbraco v17’s architecture, APIs and forward‑looking roadmap make it far better suited to AI‑driven experiences like this

The Reality of Upgrading: Why Preparation Matters

A successful v13 to v17 upgrade doesn’t start with the upgrade itself. There are key preparation steps that should ideally be handled before the major version jump:

• Migrating legacy property editors (Nested Content, Grid, Macros) to modern equivalents such as Block List or Block Grid

• Auditing third‑party packages for v17 compatibility and planning replacements where support no longer exists

• Refactoring custom APIs to align with the new Management API

• Deciding on Rich Text Editor direction (Tiptap vs TinyMCE)

• Preparing for ModelsBuilder regeneration and breaking changes introduced in v15–v17

Handled early, these steps dramatically reduce risk and complexity later. Left too late, they can turn a planned upgrade into a stressful rescue job.

Why Acting Now Makes Sense

Upgrading early provides several clear advantages:

• Full control over timelines

• Reduced technical and organisational risk

• Opportunity to modernise rather than patch

• Better budgeting and stakeholder visibility.

Waiting until v13 reaches end of life removes those options and often increases cost.

How ClerksWell Helps You Upgrade with Confidence

At ClerksWell, we specialise in complex Umbraco upgrades, particularly for organisations with bespoke development, legacy editors or long‑lived platforms.

Our approach is:

• Strategic, not rushed

• Transparent and phased where needed

• Designed to reduce risk, not shift it

Whether a single‑phase upgrade is viable or a two‑phase approach is more appropriate, we tailor the process to your platform not the other way around.