What you need to know
Microsoft ends support for .NET 8 (LTS) and .NET 9 (STS) on the same day, November 10, 2026. Apps keep running, but no further security fixes are issued. .NET 10 is the LTS release supported to November 14, 2028.
Potentially affected
Custom web applications, services, APIs, desktop tools and vendor-supplied software built on .NET 8 or .NET 9, together with their build machines and hosting environments.
DSE recommendation
DSE recommends inventorying every .NET 8 and .NET 9 workload this month and scheduling each one for retargeting, vendor replacement or a documented exception.
Microsoft ends support for .NET 8 (LTS) and .NET 9 (STS) on the same day, November 10, 2026. Apps keep running, but no further security fixes are issued. .NET 10 is the LTS release supported to November 14, 2028.
Source facts
Microsoft’s .NET support policy lists November 10, 2026 as the end of support for both .NET 8, a Long Term Support release, and .NET 9, a Standard Term Support release, and November 14, 2028 for .NET 10. LTS releases get free support and patches for three years and STS releases for two, and a system must have the latest patch installed to remain supported.
The .NET team’s announcement says applications built on .NET 8 or .NET 9 will continue to run after that date, but no new security updates will be issued and technical support ends. Upgrading means changing the project’s TargetFramework to net10.0 and also updating development and hosting environments. For third-party .NET applications, Microsoft recommends asking the developer or vendor for a version that uses .NET 10.
Applicability
Use this for in-house and custom-developed .NET applications, hosted web apps, scheduled services and line-of-business tools, and for packaged software whose vendor documents a .NET 8 or .NET 9 runtime dependency.
DSE recommendation
DSE recommends inventorying every .NET 8 and .NET 9 workload this month and scheduling each one for retargeting, vendor replacement or a documented exception. Record the runtime, hosting platform, owner and test plan per application. Retarget to net10.0 in a branch, review the published breaking changes, update build agents and servers, and ask each software vendor in writing for a .NET 10 release date. Any workload still on .NET 8 or .NET 9 after November 10 needs an owner-approved risk acceptance and compensating controls.
Verification
Confirm the deployed application reports the .NET 10 runtime, run its regression and security tests in staging, and check that build pipelines no longer restore .NET 8 or .NET 9 SDKs. After cut-over, remove unused .NET 8 and .NET 9 runtimes from servers and record the change.
Official references
Microsoft .NET — .NET and .NET Core Support Policy. .NET Blog — .NET 8 and .NET 9 will reach end of support on November 10, 2026. Reviewed October 18, 2026.
Review the official source
Microsoft .NET — .NET and .NET Core Support Policy · Verified October 18, 2026
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