Your .NET 8 and .NET 9 Apps Lose Support on November 10, 2026

Microsoft has confirmed the end-of-support date for two widely-used runtimes: .NET 8 and .NET 9 both reach end of support on November 10, 2026. After that day, Microsoft stops shipping security updates and technical support for either version (Microsoft's announcement). Your applications won't suddenly stop running — but they stop being protected.

What "end of support" actually means

It's easy to read this as a version number ticking over. It isn't. From November 10, 2026:

• No more security patches. New vulnerabilities discovered in the runtime simply won't be fixed. Your app inherits every unpatched CVE, indefinitely.
• No technical support. If something breaks in production, Microsoft is no longer a backstop.
• The ecosystem moves on. Libraries, SDKs, and hosting platforms drop support for old target frameworks too — so staying put gets harder, not easier, over time.

The apps keep working, which is exactly what makes this dangerous: there's no outage to force your hand, so it's easy to defer — right up until a security questionnaire, an auditor, or a live CVE turns a calm upgrade into an emergency.

Why this is a compliance issue, not just a technical one

Running an unsupported runtime is increasingly a business risk, not a developer preference. SOC 2, PCI-DSS, HIPAA, and most cyber-insurance renewals expect you to be on supported, patched software. An end-of-support framework is the kind of finding that fails an audit, stalls an enterprise deal, or spikes an insurance premium — often at the worst possible moment.

The part most teams underestimate

In our experience, almost no one is on a single clean version. A typical estate is a mix: a few services on .NET 8, an internal API still on .NET 6 or .NET Core 3.1 (already out of support), and a billing or reporting app quietly running on .NET Framework 4.x. The November 2026 date is a useful forcing function to look at the whole estate — not just the one app that happens to be on .NET 8.

The good news: for modern .NET, this is usually a small move

If you're already on .NET 8 or .NET 9, the destination is .NET 10 — a Long Term Support release supported through November 2028. For a well-maintained codebase, the upgrade can be as light as retargeting to net10.0, updating packages, and running your test suite. That's the opposite of a rewrite: one focused effort buys you two more years of security and support.

The catch is the phrase "well-maintained." The upgrade gets real when there's no test coverage to prove nothing broke, when third-party dependencies bring their own breaking changes, when the app is business-critical and can't go down, or when you're jumping several versions — or coming off .NET Framework entirely. That's precisely the work we do every day.

How we handle it

This is core to what Malaika does: legacy .NET modernization, done incrementally and safely. For an end-of-support upgrade, that looks like:

• A .NET upgrade assessment. We inventory every application and service, flag what's already or soon out of support, and map a prioritized, costed path to .NET 10. You get a clear picture before you commit budget.
• Incremental, production-safe execution. We upgrade the way we modernize everything — one piece at a time, no big-bang, no downtime. Your business keeps running while the foundation moves underneath it.
• Dependencies and breaking changes, handled. We take on the package upgrades, the .NET 10 breaking-change work, and the tooling, so your team doesn't lose weeks to it.
• Proof before cutover. We verify that behavior still matches before real traffic moves — the same discipline behind our zero-downtime API modernizations, where the switch was a non-event.
• A plan to stay current. We set you up so the next end-of-support date is a routine bump on the roadmap, not a fire drill.

The smart time to act is now, while it's calm

November 10, 2026 sounds far off, but upgrade work competes with everything else on your roadmap — and the closer it gets to the deadline, the more it costs in urgency, overtime, and risk. Making it a planned, budgeted line item this quarter is the difference between a controlled upgrade and a scramble.

If you're not sure what you're running, or where the exposure is, that's the perfect place to start. We'll assess your .NET estate, tell you plainly what needs to move and by when, and give you a path that fits your business — not a rewrite you didn't ask for.