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.NET 8 support ends. Upgrade or rebuild?

On 10 November 2026 Microsoft ends support for .NET 8 and .NET 9. After that date there are no more security updates and no more bug fixes. This affects every ASP.NET Core application, every Blazor app and every Web API service still running on either version.

The obvious answer is the upgrade to .NET 10. For many applications it is also the right one. Before you sign off the budget, it still pays to check whether the application will be in better shape afterwards than it is today. That is what this post is about.

What happens on 10 November

.NET 8 is an LTS release from November 2023 with three years of support. .NET 9 is an STS release from November 2024 with two years of support. Both end on the same day. The successor .NET 10 is LTS again and supported until 14 November 2028. The current dates are in Microsoft's support policy.

Your application keeps running on 11 November. What stops are the monthly patches. Every vulnerability found in the runtime or in ASP.NET Core after that date stays open on your side. At the next security audit, or with a client who asks for proof of patching, it becomes a problem.

One distinction, because the two get mixed up a lot. The classic .NET Framework 4.8, which ASP.NET Web Forms runs on, is not affected by this date. Its support follows the Windows lifecycle. Web Forms has a problem of its own, though. It gets no new features and cannot be moved to modern .NET. If you run a Web Forms application, you face the same question as here, just without a deadline.

For most teams the upgrade is right

Going from .NET 8 to .NET 10 is usually a manageable step. Raise the target framework in the .csproj, update the NuGet packages, work through the breaking changes, test. If your application works, the team knows the code and new features ship in reasonable time, do exactly that. A rebuild would only add cost in that situation.

What tends to surprise people during the upgrade are commercial packages. UI components from Telerik, DevExpress or Syncfusion, reporting tools, Hangfire Pro or NServiceBus all need a version that supports .NET 10. Depending on the licence model that means a renewal or a new contract. A good moment to check how much of it you actually use.

When the upgrade is the wrong question

An upgrade keeps the application secure. Features, interface and maintainability stay exactly the same. If any of the following applies to you, the upgrade means paying for everything to stay as it is.

New features take months. Every change causes follow-up bugs, so hardly anything changes anymore.
The interface slows people down. Forms with hundreds of fields, pages that reload after every save, and error messages only at the very end.
Integrations are missing. No automatic emails, no connection to the CRM, data gets exported by hand.
The knowledge sits with one person. When they leave, nobody dares to touch the code.
Licences cost more than development. Components, reporting and messaging add up every year.

An example from a laboratory

We are seeing exactly this situation at a laboratory client right now. The .NET backend runs reliably and has done its job for years. The interface is a pain for the people who work with it every day. Some input forms have around 200 fields.

This is where server-rendered UX hits its limit. With 200 fields you want sections that collapse, checks while you type, autosave and suggestions from earlier entries. With classic page reloads all of that is hard to build.

Our proposal there is smaller than a rebuild. The backend stays and becomes an API. In front of it goes a new frontend built for exactly these forms. The risk sits where the problem sits, and the business logic that has worked for years stays untouched.

Laravel as an alternative, and when it is none

If parts of the application really should be rebuilt, Laravel is a good choice for many business applications. The framework costs no licence, hosting is cheap, and typical requirements like roles and permissions, forms, approvals, background jobs and integrations come as ready, maintained building blocks. With Inertia and Vue you can build very large forms that feel like a desktop application.

None of this has to happen at once. A proven pattern is to keep the .NET backend running as an API, rebuild the frontend, and then move individual modules over step by step. Each step stands on its own, and you can stop after any of them. How we approach this is on our legacy modernization page.

There are also clear cases where .NET stays the better choice. If you have your own .NET team, if the application is deeply tied into Active Directory, Azure and the Microsoft stack, or if it depends heavily on Windows components, stay with .NET and invest the money there. Switching technology only pays off when it solves a concrete problem.

What you can do before 10 November

Take stock. On the server, dotnet --list-runtimes shows which runtimes are installed. In the code, the version is in the TargetFramework of the .csproj files.
Check your packages. For every commercial NuGet package, find out whether there is a .NET 10 version and what the licence costs.
Decide per application. Is the upgrade enough, or does it need a plan for the frontend or a partial replacement?
Security first. If time gets short, move to .NET 10 first and reassess afterwards. With support in place, every bigger decision gets easier.

Want to know whether the upgrade is enough for your application? We take a look and tell you honestly what is worth doing. Book a free discovery call →

Frequently Asked Questions

When does .NET 8 support end?

On 10 November 2026. .NET 8 is an LTS release from November 2023 with three years of support. After that Microsoft ships no more security updates or bug fixes. Its successor .NET 10 is supported until 14 November 2028.

Why does .NET 9 reach end of support on the same day as .NET 8?

.NET 9 is an STS release with two years of support starting November 2024. .NET 8 is an LTS release with three years starting November 2023. Both periods therefore end on 10 November 2026.

Will my .NET 8 application keep running after 10 November 2026?

Yes, the application keeps running unchanged. Microsoft just stops shipping patches. Vulnerabilities found in the runtime or in ASP.NET Core after that date stay open, which becomes a problem in security audits and in client contracts that require patching.

Is ASP.NET Web Forms affected by the .NET 8 end of support?

No. Web Forms runs on the classic .NET Framework 4.8, whose support follows the Windows lifecycle. Web Forms gets no new features, though, and cannot be moved to modern .NET, so the modernisation question applies there as well.

When is a new frontend worth more than just upgrading to .NET 10?

When the backend runs reliably but the interface slows down daily work, for example with input forms of hundreds of fields. The .NET backend then stays as an API and only the frontend gets rebuilt. That keeps the risk far lower than a full rebuild.

Is Laravel an alternative to .NET?

For business applications with forms, roles, approvals and integrations, yes. Laravel costs no licence and hosting is cheap. Teams with their own .NET developers, or applications deeply tied into Active Directory, Azure and the Microsoft stack, are usually better off upgrading to .NET 10.