.NET 11 RC1 Is Out as .NET 8 and .NET 9 Approach End of Support on November 10, 2026

On September 8, 2026, Microsoft's .NET team published .NET 11 Release Candidate 1, the first build of the next .NET version that Microsoft says can be used for production applications. The final release has not shipped yet.

The timing matters for a less exciting reason. Microsoft's .NET support policy lists the same end of support date, November 10, 2026, for both .NET 8 and .NET 9. If your web application, API or internal system runs on either version, the choice of technology stack version is about to become a security question rather than a preference.

This article separates what is available now from what is only scheduled, and explains what an owner of .NET software should do before November.

What Microsoft released on September 8, 2026

According to the .NET team's announcement, .NET 11 Release Candidate 1 includes changes across the libraries, runtime, SDK, C#, ASP.NET Core and .NET MAUI, among other areas. The post highlights items such as SignalR authentication APIs and OpenAPI improvements in ASP.NET Core, testing improvements for mobile targets in the SDK, and crash reporting on Unix in the runtime. Microsoft states that the release is supported in Visual Studio 2026 Insiders and in Visual Studio Code with the C# Dev Kit.

On the same day, Microsoft shipped routine servicing updates for the versions already in production. The support policy page lists 10.0.12, 9.0.20 and 8.0.31 as the latest patch versions, each dated September 8, 2026.

It is worth being precise about status. .NET 11 is a release candidate, not a generally available product. The .NET team's release discussion on GitHub describes RC1 as the first of two release candidates, and the support policy page lists RC1 itself as supported only until October 13, 2026.

What go-live support does and does not mean

Microsoft's announcement says RC1 comes with a "go-live support license" so that teams can use it for production applications. In practice this means Microsoft will support production use of the release candidate, which is not true of earlier previews.

It does not mean the release is finished. A release candidate can still receive fixes before general availability, and each candidate has a short support window of its own. A team that deploys RC1 is committing to move to the next candidate, and then to the final release, promptly. For most business systems, go-live support is a signal to begin testing, not a reason to put RC1 in front of customers.

The deadline that matters more: November 10, 2026

Microsoft's support policy page shows .NET 8, a Long Term Support release from November 14, 2023, and .NET 9, a Standard Term Support release from November 12, 2024, both reaching end of support on November 10, 2026. Both are already listed in the maintenance phase.

The same page defines what end of support means: Microsoft no longer provides fixes, updates or online technical assistance. It also says that using out-of-support versions may put applications, application data and the computing environment at risk, and it recommends against doing so.

An application does not stop working on November 11. It keeps running exactly as before, which is the problem: vulnerabilities found in the runtime after that date are fixed in supported versions only. Many applications built over the last three years target .NET 8 because it was the long-term option at the time, so this date is likely to affect a lot of systems at once.

.NET 10 or .NET 11: where to move

There are two destinations, and they differ in status today.

.NET 10 is available now

The support policy page lists .NET 10 as a Long Term Support release, published on November 11, 2025, in the active support phase, with end of support on November 14, 2028. Microsoft's policy is that LTS releases are supported for three years after initial release.

.NET 11 is scheduled, not released

The .NET team's release index on GitHub lists .NET 11 as a Standard Term Support release with a release date of November 10, 2026. Until Microsoft ships it, treat that as a planned date. The RC1 announcement itself does not state a general availability date. Under the support policy, STS releases are supported for two years.

The difference between two years and three years of support is smaller than it used to be, so the decision is mostly about risk and timing. .NET 10 has been in production use for almost a year and its libraries and hosting platforms have had time to catch up. .NET 11 offers newer features but will be brand new on the day .NET 8 and .NET 9 lose support.

What this means for your business

The following is our reading of the situation, not a statement from Microsoft.

If your application runs on .NET 8 or .NET 9, the practical target for most teams is .NET 10. It is released, it is the long-term version, and an upgrade to it can be finished and tested before November 10. Waiting for .NET 11 means upgrading to a version on its first day while your current version expires on the same day, which leaves no margin for surprises.

If you are planning a new build that will launch in 2027, the calculation changes. Starting development on .NET 10 and reviewing .NET 11 after it has had a few servicing updates is a reasonable path, and so is building on the release candidate if your team is comfortable tracking it closely.

The effort involved is usually moderate for a well-maintained application. Microsoft's upgrade guidance notes that the only required source change is the target framework setting in each project file, after which the new SDK reports anything else that needs attention. The real cost drivers are elsewhere: third-party packages that have not been updated, breaking changes that affect your code, the depth of your automated tests, and how many environments, build pipelines and container images need to change. Applications that skipped earlier upgrades, or that have few tests, take longer.

If an outside vendor maintains your system, this is also a contract question. Check whether framework upgrades are covered by your support agreement or treated as separate work. Our guide on how to outsource software development covers what to put in a maintenance agreement.

What to do next

A short, ordered plan is enough for most organizations:

• Find out which .NET version each of your applications and background services actually runs on, including older internal tools.
• For anything on .NET 8 or .NET 9, schedule the move to .NET 10 with a completion date before November 10, 2026.
• Ask your developers to list package dependencies that do not yet support the target version, since these are the most common blockers.
• Update build pipelines, container base images and hosting configuration together with the code. Microsoft's guidance points out that hosting environments that include the runtime need the new runtime installed, and cloud services need a configuration change.
• If you are interested in .NET 11, run your test suite against RC1 in a separate branch now, and decide after general availability.

Whatever you choose, keep applying the monthly servicing updates to the version you are on until the upgrade is complete.

Conclusion

.NET 11 Release Candidate 1 has been available since September 8, 2026 with go-live support, and the final release is listed for November 10, 2026. That same date is when Microsoft's support for .NET 8 and .NET 9 ends. For most businesses the release candidate is something to test, and the end of support date is something to act on, with .NET 10 as the stable place to land.

If you are not sure which version your software uses or how large the upgrade would be, you can contact us and we will help you scope it.