Your computer is set to UEFI boot mode but Secure Boot is OFF (Disabled).So, if you get the error 'Secure boot is not supported' or 'Secure boot is not available', then one of the following is probably happening: Microsoft has made secure boot a prerequisite for users who want to upgrade to Windows 11. Windows 8, 8.1 & 10 are designed to operate also in UEFI boot mode, which uses the GUID Partition Table (GPT), in order to take advantage of the advanced features offered by the UEFI, such as the 'Secure Boot' security feature. Windows 7, Vista and XP used to operate in Legacy boot mode (also known as 'CSM' Mode), which uses the Master Boot Record (MBR) Partition table. Secure boot is available on almost all modern computers and is built into the UEFI (Unified Extensible Firmware Interface), to prevent malware from taking over the computer during the boot process. Microsoft, starting with Windows 8, supports a new security feature called Secure Boot. If you try to install Windows 11 and you can't because Secure Boot is Unsupported or Not Available, continue reading below.

Windows 11 secure boot