Microsoft officially ended support for Windows 10 on October 14, 2025, which means these PCs no longer receive monthly security updates published during "Patch Tuesday." However, they continue to function, as the end-of-support date did not include a "kill switch," which would disable the operating system. To continue receiving security updates, users can enroll in the Extended Security Updates (ESU) program, which provides critical and important security patches until October 12, 2027 for individuals and October 10, 2028 for businesses. The ESU program does not include new features, bug fixes, or technical support. Registration is free for individuals in the European Economic Area (EEA) and those who back up their settings in the Microsoft cloud or use 1,000 Microsoft Rewards points. Others can pay approximately 30 euros. Businesses must purchase licenses through the volume licensing program or a CSP provider, with costs increasing each year. For users who prefer to upgrade to Windows 11, most PCs sold in the last 15 years can run the newer operating system. PCs sold with Windows 10 can generally be upgraded after a registry change. However, older PCs or those with unusual configurations may require a third-party utility. Microsoft added restrictions starting with Windows 11 version 24H2, requiring a processor that supports specific instructions: SSE4.2 and PopCnt. Most PCs with Intel processors from 2009 or later and AMD processors from 2013 or later meet these requirements. It is impossible to upgrade to a supported version of Windows 11 on a PC manufactured in 2008 or earlier. To upgrade to Windows 11, users must ensure their PC meets certain requirements, including a TPM version 2.0 and UEFI mode. If these requirements are not met, users can use workarounds such as a registry change or the free utility Rufus. The registry change involves modifying a key in the Windows registry to bypass the processor compatibility check. This allows installation on a PC with an older TPM (version 1.2) and requires Secure Boot to be enabled. Alternatively, Rufus can be used to create a bootable USB drive that automatically incorporates changes to bypass compatibility checks. However, Rufus cannot bypass the restrictions introduced with the Windows 11 version 24H2 if the processor does not support the required instructions. Users should ensure they have sufficient free space on their system drive, with a minimum of 25 to 30 GB. If they do not have enough free space, they may need to uninstall applications or delete files. Additionally, users should check their PC's BIOS mode and TPM status using tools like Msinfo32.exe and Tpm.msc. If a PC does not have a TPM or cannot be configured to UEFI mode, alternative methods may be necessary.