On 10 November 2026 Microsoft stops issuing security updates for .NET 8, PowerShell 7.4 and Windows 11 Enterprise and Education version 23H2. Most Perth offices will never notice, because their staff use Office and a browser, not .NET directly. The exception is any business running custom or industry-specific software built on .NET 8: that software keeps working after the date, but the runtime underneath it stops being patched. The practical job for the next few weeks is to find out whether you have any, and to ask the software supplier for their plan.
What actually ends on 10 November
Microsoft's lifecycle page lists the following as reaching end of servicing on 10 November 2026:
- .NET 8 (LTS): the runtime many business applications, internal tools and web portals are built on.
- PowerShell 7.4 (LTS): the modern, cross-platform PowerShell used in scripts and automation. This is separate from the Windows PowerShell 5.1 that ships with Windows.
- Windows 11 Enterprise and Education, version 23H2, and Windows 11 IoT Enterprise 23H2.
- Azure Functions in-process model for .NET apps, which Microsoft's Azure updates page also dates to 10 November 2026.
After that date there are no new security updates, no non-security updates and no assisted support from Microsoft for these versions.
Why a runtime matters to a small business
Think of .NET as the engine inside a piece of software. You rarely see it, but your practice management system, job costing tool, booking portal or a custom app written by a contractor years ago may depend on it.
When the engine stops getting security fixes, any newly discovered flaw stays open. Attackers pay attention to end-of-support dates for exactly this reason: an unpatched component is a predictable target. It also tends to matter later, when a cyber insurer, a client's security questionnaire or an audit asks whether everything in your environment is supported.
Software that was built to carry its own copy of .NET is just as exposed as software that uses the version installed on the computer. Both depend on the supplier shipping an update.
A simple five-step check
- List your line-of-business software. Include anything a contractor wrote for you, internal websites, and apps that run on a server in the back room or in Azure.
- Ask each supplier one question in writing: "Which version of .NET does this run on, and when will you support a newer one?" Reputable vendors will answer straight away. A vague answer is useful information too.
- Check your Azure services. If you host functions or web apps in Azure, ask whoever built them whether they use the in-process model or .NET 8.
- Check your Windows 11 editions. Windows 11 Pro and Home follow a different schedule from Enterprise and Education. If you are not sure which edition your computers run, an inventory will tell you in minutes.
- Write the findings down with a date and an owner, so the upgrade is a planned project rather than a scramble.
What to do if something depends on .NET 8
You usually have three options, and the right one depends on how critical the software is:
- Upgrade the application to a supported .NET version. This is the best outcome and often a modest job for the supplier.
- Isolate it while you wait: restrict who can reach it, keep it off the open internet, and make sure backups are tested.
- Replace it if the supplier has gone quiet. An abandoned application is a risk regardless of what it runs on.
Do not leave it until after 10 November and hope. Upgrades to a new runtime need testing, and testing takes longer than people expect.
How this fits with the other October and November deadlines
This sits alongside the dates we have already covered, including the October 2026 end-of-support changes for Exchange, Office and Windows Server and the Windows 11 24H2 cut-off. If you want one view of everything that is ageing in your environment, a managed IT services provider keeps that inventory current so deadlines like these do not catch you out. The wider Microsoft 365 guide for Perth businesses explains where the cloud side of your licences fits.
Need a hand working out what you have?
If you are not sure what your business software runs on, we can help you build the inventory and put questions to your suppliers. Computer Mechanics has supported Perth businesses since 1997, so get in touch or call (08) 9325 1196.
Source: Microsoft Lifecycle, "Ending Support in 2026" (learn.microsoft.com/lifecycle/end-of-support/end-of-support-2026).