You ran the command, and instead of BIOS you got a flat refusal: the firmware UI is not supported. That error is not a broken PC — it is Windows telling you this install has no UEFI door to open.
The full message reads Boot to firmware UI is not supported by this system's firmware.(1) and it appears the instant shutdown /r /fw /t 0 meets a machine it cannot help. In plain words: the /fw request asks the UEFI firmware to open its setup screen on the next boot, and this PC is not running UEFI firmware mode for its Windows install. The overwhelmingly common cause is a Legacy BIOS (CSM) install of Windows. A virtual machine can produce the same message for a different reason. This page shows how to confirm which situation you are in, and which BIOS entry routes honestly remain — because no command, registry edit or tool can add a UEFI flag to a Legacy install after the fact.
Do not guess — the answer is written in Windows already, exactly as the video shows for checking BIOS mode.
msinfo32, press Enter/fw flag has nothing to attach toPlenty of perfectly UEFI-capable machines carry a Legacy Windows install. It happens when the install USB was booted in Legacy/CSM mode years ago, when a disk was cloned from an older PC, or when CSM was left on in setup and the installer quietly took the old path. The hardware is modern; the install mode is not. Converting an existing install from Legacy/MBR to UEFI/GPT is a real project (Microsoft ships the mbr2gpt tool for it), not a side effect of this command — and it should be planned with a full backup, never improvised just to use a shortcut.
The same error appears inside VMs whose virtual firmware is Legacy:
/fw can never work inside them. Generation 2 VMs are UEFI and accept the commandA Legacy PC still has a BIOS — it is only the Windows-side shortcut that is missing.
And one promise to ignore wherever you meet it: no downloadable tool converts a Legacy install's firmware flag or makes /fw work on it. The error is the honest end of that road.
The command, the UEFI check and the restart into BIOS setup — shown live on a real PC, step by step.
▶️ Watch Full VideoBecause the Windows install, not the hardware, decides the mode. If Windows was installed or cloned while CSM/Legacy was enabled in setup, it installs the old way even on brand-new hardware. The PC is not faulty — the install simply took the Legacy path.
Only if the reinstall is done in UEFI mode — booting the install USB as a UEFI device with CSM off and installing to a GPT disk. A reinstall done the same Legacy way reproduces the same error. It is a real fix, but a heavy one just for this shortcut.
Probably related. Error 87 usually means the command was tried inside a Remote Desktop session, which shutdown does not support. Access denied means the prompt was not elevated. The (1) message on this page is the specific signature of a non-UEFI install.