Downgrade from Insider Preview ➜ Stable without wiping data

[Othmane-ElAlami]

Hello everyone,

I'm currently running Windows 11 Pro Insider Dev build 27881 (rs_prerelease), and I need to switch back to the stable public release 24H2 build 26100.1742, while preserving all applications and user data.

Objective:

Perform an in-place downgrade, essentially rolling back to an older build, similar to a regular repair install but targeting a lower build number, with all programs and files intact.

Queries:

1. Is there any supported or semi-supported method, such as a command-line switch, registry tweak, or unattend.xml file modification, that can bypass the build version check?
2. Has anyone successfully slipstreamed a cumulative update (CU) into the 24H2 ISO to artificially raise its revision number beyond Canary build 27881, thus tricking Windows Setup into allowing an in-place "upgrade" to the lower base build?

Any helpful tips, scripts, or experiences shared are greatly appreciated!
Thanks!