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Win11 System-Requirement Bypass

Skip the TPM 2.0 / Secure Boot / 4 GB RAM / CPU compatibility gate that otherwise blocks clean installs of Windows 11 on unsupported hardware.

Two layers, both shipped to every Win11 product by default:

  1. Registry tweak via autounattend windowsPE pass — always on for Win11.
  2. DLL patch in install.wim — only when bypass DLLs are provided as a private-repo secret.

Layer 1: registry tweak (always on)

autounattend/base.xml writes three LabConfig DWORDs into HKLM\SYSTEM\Setup\LabConfig before the appraiser compatibility check runs:

BypassTPMCheck         = 1
BypassSecureBootCheck  = 1
BypassRAMCheck         = 1

Verified working for 21H2 → 23H2 across all SKUs. For 24H2+ it usually still works on Home/Pro, but Microsoft has been seen to block it on some Enterprise SKUs. The DLL patch (layer 2) covers that.

Layer 2: DLL patch (opt-in, version-locked)

scripts/build/bypass_win11_requirements.py mounts install.wim and replaces:

Windows/System32/appraiserres.dll
Windows/System32/appraiser.dll

with patched versions that return "compatible" for any hardware.

Source DLLs

The DLLs are version-specific and are vendored directly in this repo at bypass/<product>/ (this replaces an earlier private-repo + base64-secret design — see the decision record in bypass/README.md):

bypass/
  win11-24h2/
    appraiserres.dll
    appraiser.dll
  win11-25h2/
    appraiserres.dll
    appraiser.dll

You can grab them from any community source (e.g. AveYo/MediaCreationTool's Skip_TPM_Check_on_Dynamic_Update.cmd fetches them, or use the bypass11/ directory directly from a release tarball). The pair must be version-matched to the target build — see the locking notes in bypass/README.md.

Wiring

No secrets or extra setup: drop the two DLLs into bypass/<product>/ in this repo and commit. At build time the "Check Win11 bypass policy" step (scripts/build/bypass_policy.py) reads the needs_dll_bypass flag for the product+edition from config/editions.yaml:

  • flag not set → DLL steps skipped entirely (registry tweak only)
  • flag set + DLLs present → staged into artifacts/bypass/ and patched into the WIM
  • flag set + DLLs missing → build fails fast with a pointer to bypass/README.md

How the build flow works

convert.sh          # UUP -> ISO
wimlib-imagex       # inject Intel RST drivers (build.yml step, Linux)
bypass_win11_requirements.py   # DLL patch (optional) + commit WIM
repack.sh           # install.wim + autounattend.xml -> final ISO
                     # autounattend carries the LabConfig registry keys

Testing

pytest tests/test_bypass_win11.py tests/test_autounattend_bypass.py -q

The bypass script is fully mocked. The autounattend test parses autounattend/base.xml and asserts the three LabConfig keys are present in the windowsPE pass.

Verification on real hardware

After installing a built ISO on a TPM-less / 4 GB RAM / no-Secure-Boot machine, you should see the install proceed straight to the partition screen with no "This PC can't run Windows 11" dialog. If you see the dialog, the registry tweak got stripped — check that the autounattend/base.xml <RunSynchronousCommand> block made it into the final ISO's autounattend.xml.