.NET 8 and .NET 9 reach end of support in November 2026 – plan your move to .NET 10 LTS now

If your company runs a piece of custom software, an internal tool or a web application on .NET, there is one date you should put in the calendar: 10 November 2026. On that day, official support ends for two widely used .NET versions at once – for .NET 8 and .NET 9 simultaneously. After that, there are no more security updates. Plan early and this is a non-event. Ignore it and you risk an expensive last-minute scramble.

Why do two versions end on the same day?

Microsoft uses two support models for .NET:

• LTS (Long Term Support): three years of support. Intended for stable, long-lived systems.
• STS (Standard Term Support): two years (24 months) of support. For those who want the newest features quickly.

That leads to a quirk:

• .NET 8 is an LTS release, published in November 2023. Three years later, on 10 November 2026, its support ends.
• .NET 9 is an STS release, published in November 2024. Two years later it reaches end of support on the very same day.

This is no coincidence but a consequence of the fixed support windows – and it is exactly why it hits two large groups of users at the same time.

What "end of support" actually means

End of support does not mean your software stops overnight. It keeps running technically. But:

• No more security updates. Newly discovered vulnerabilities will no longer be patched for these versions.
• No more bug fixes and no official support from Microsoft.
• Compliance pressure. For GDPR, NIS2, cyber insurance and audits, outdated unpatched software increasingly counts as an avoidable risk.

The first point is the dangerous one. An application that "works" but no longer receives security updates is an open door – and often unnoticed, until something happens. Unlike operating systems, modern .NET has no paid Extended Security Updates (ESU) as a stopgap: once the date passes, that's simply it. The clean path is therefore to update to a current version – and that is the most economical route anyway.

The good news: .NET 10 LTS is already here

You do not have to wait for a new version. .NET 10 was released in November 2025 and is the current LTS version – supported until 14 November 2028. That makes .NET 10 the natural target for anyone on .NET 8 or .NET 9 today:

• If you are on .NET 8, this is the predictable LTS-to-LTS jump.
• If you are on .NET 9, you only ever had short-term support anyway, and moving to .NET 10 buys you three more years of stability.

How to approach the update

Moving from .NET 8/9 to .NET 10 is in almost all cases much simpler than the notorious jump from the old .NET Framework to modern .NET. It is still project work that needs testing, though. A realistic plan:

1. Take inventory. Which applications, services and APIs run on .NET, and on exactly which version? Often that alone is a surprise.
2. Set priorities. What is reachable from outside or processes sensitive data? Those systems first.
3. Check dependencies. The libraries you use (NuGet packages) must support .NET 10. Usually that is no problem, but it should be confirmed up front.
4. Update in a test environment and test thoroughly before anything goes into production.
5. Build in a time buffer. November 2026 sounds far away – but it isn't, once holidays, other projects and a clean test run get in the way.

My advice: treat 10 November 2026 as a deadline with lead time, not as the target date. Start in the summer or autumn of 2026 and you have plenty of room.

A word for Recklinghausen and the Ruhr region

Many small and medium-sized businesses here in the region had a tailored piece of software built years ago – a pricing tool, an order management system, a customer portal. Such applications are unobtrusive and valuable, but easily forgotten when it comes to updates, because "they just work". These are exactly the systems to take a deliberate look at now. A quick check of which .NET version they run on costs little – an unpatched gap later can get expensive.

Conclusion

10 November 2026 affects two .NET versions at once: .NET 8 and .NET 9. With .NET 10 LTS the successor is ready, and the move is easy to plan – as long as you don't put it off until the final week. Find out now where .NET is in use across your business, and set a calm, deliberate roadmap.

Not sure which .NET version your software uses or how much effort an update would take? In a free initial consultation we look at it together and estimate the effort realistically – without the jargon.