How can I update Windows 11 23H2 to 26H2 or 26H1 now?

Upgrading from 23H2 to 26H2 is designed to be straightforward, but there are critical errors you need to avoid to prevent a failed installation or an unstable system.

Attempting to upgrade too early

What It Means: The general availability of 26H2 is expected between late September and October 2026. Trying to force it before the official rollout or via unofficial preview builds (e.g., through unsupported methods) can lead to instability. Microsoft uses a phased rollout to catch hardware-specific bugs first.

How to Avoid It: Wait for the official release and for Windows Update to offer it to your device. Only use preview builds on non-critical machines

Forcing the upgrade via ISO instead of the Enablement Package

What It Means: Because 23H2, 24H2, and 25H2 share the same core system files, the upgrade to 26H2 is delivered as a tiny Enablement Package (eKB) that simply "turns on" the new features. This package is only 174 KB and installs like a regular monthly update. Using a full ISO will trigger an unnecessary and lengthy full OS reinstall, which carries a much higher risk of failure.

How to Avoid It: Let Windows Update handle the upgrade. When you update Windows 11 23H2 to 26H2 via the enablement package, the process is quick and requires only one restart.

Ignoring driver compatibility issues

What It Means: Starting with the 26H2 base (build 26300), Windows will enforce stricter driver signing rules. This change, which has been in the works for years, will block any kernel-mode driver that is not signed under the Windows Hardware Compatibility Program, effectively breaking legacy hardware and peripherals with unsigned or outdated drivers. You have a 100-hour "audit mode" after installation to identify and replace incompatible drivers before they are fully blocked.

How to Avoid It: Before you upgrade, inventory all your hardware (especially older peripherals, security tools, and virtualization agents) and check with the manufacturer for signed drivers. Do not attempt to update Windows 11 23H2 to 26H2 on a machine with known legacy driver dependencies.