.NET 3.5 Offline Installer: Adding the Feature Without Internet

You may need the full offline installer for .NET Framework 3.5 — commonly required by older applications that target .NET 2.0 or 3.5, or in WSUS environments where you can’t simply enable the feature through Windows Update.

Getting the Official Installer

Rather than relying on a third-party mirror, download directly from Microsoft’s official .NET Framework download page (search “download .NET Framework 3.5” on microsoft.com), which hosts the current offline installer for Windows 8 through current Windows 10/11 releases.

Alternative: Enable via DISM (No Download Needed)

If your machine has internet access, or you have access to Windows installation media, you can enable .NET 3.5 directly without a separate download:

DISM /Online /Enable-Feature /FeatureName:NetFx3 /All

If the machine has no internet access and you have Windows installation media (ISO or USB), point DISM at the media’s sources\sxs folder instead:

DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:D:\sources\sxs /LimitAccess

(adjusting the drive letter for your mounted media). This is generally the most reliable method in WSUS-managed environments, since it doesn’t depend on Windows Update at all.

A Big Change Is Coming: Windows 11 26H1 (Updated for 2026)

Everything above is still exactly correct on Windows 10 and on Windows 11 up to and including 25H2 — the DISM syntax and the offline sources\sxs media source are unchanged. But Microsoft has confirmed a real change for Windows 11 26H1 (now shipping): starting there, .NET Framework 3.5 is no longer available as a Windows Feature-on-Demand at all, so DISM-based enabling — both the online method and the offline /Source media method — is no longer supported. The only supported path on 26H1+ is a version-specific standalone installer distributed via a Microsoft redirect link rather than the classic Download Center page, and ASP.NET 3.5 additionally needs a separate Enable-ASPNet35.ps1 script run after install. If you’re still on Windows 10, Windows 11 24H2, or Windows 11 25H2, none of that affects you yet — the steps above keep working as documented. It only matters once a machine moves to 26H1.

Resources

• WSUS
• Download Dot Net 3.5 Offline Installers
• How to Reinstall .NET Framework on Windows Server 2022
• Windows 8.1 Dot.Net 3 Feature Enable using Operating System media offline
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