Second System for Windows 8.1
Added 2025-10-14 19:39:37 +0000 UTCSecond System for Windows 8.1 is now here! Run many modern applications including the latest Firefox, Google Chrome and Steam clients, productivity applications like Kdenlive and more! And limited AVX emulation for when your older system needs an extra push.
Our work is far from done, however. Compatibility with Windows 10, 32 bit versions of Windows, D3D12, modern network cards, modern toast notifications and more is still on the way.
Some Installation Notes:
Windows 8.1 requires that some system DLL substitutes be present in the system32/syswow64 folders. For this reason, administrator privileges are required to install this version of Second System. Elevation will be prompted automatically upon running InstallSecondSystem.cmd.
Revised 2025-10-16 (1323 UTC-4, but only noted here at 1517 UTC-4 due to an omission) to change the 32-64 process hook and fix an issue in the wrapper for cfgmgr32.dll.
Revised 2025-10-25 (0308 UTC-4) to include subsystem version patching support for higher (2020+) update levels, definitions for several API set DLLs, fixes for Office 2019 applications and some reliability improvements regarding export forwards (primarily impacting version.dll):
Comments
There was an error in earlier iterations of the manual; it should be "DefaultProfile". I have also updated Second System to version 2.2 as of last week which should be more stable than previous iterations.
win32
2025-11-12 17:24:44 +0000 UTCI can't make it act Passive on new apps by default, even though I added "DefaultValue" to "Passive" in registry; so it tries to force compatibility on every new app and most of them crash. Do I do something wrong?
Alex O
2025-11-12 17:05:38 +0000 UTCWhich update level are you at? Looks like the patch may not be effective at that level.
win32
2025-10-18 15:13:29 +0000 UTCWindows 8.0 is structurally compatible with this version but some ntdll functions are missing. When they're added, it should be part of this package.
win32
2025-10-18 15:13:00 +0000 UTCUnfortunately, the MajorOperatingSystemVersion & MajorSubsystemVersion check bypass in the Optional Header does not work for me and I have to constantly change it through CFF Explorer. https://postimg.cc/18pHZsF7 Hopefully this will be fixed in the future.
Артем Пономарев
2025-10-18 14:31:20 +0000 UTCI've seen you mentioned future support for Windows 10, is Windows 8.0 also planned (it should be easier to do and also probably needs Second System more than 10 for now)
TSNH
2025-10-16 20:08:48 +0000 UTC
