Win7/Win8.1 upgrade Win10 official version is a recent hot spot. After many users have joined Windows 10, it is inevitable that users will need to downgrade to the original Windows7/Windows 8.1 system for various reasons. According to the general idea, if you want to downgrade to a lower version of the operating system, it is basically a simple and rude formatted reloading method. However, in the Win10 era, since a large number of users were upgraded from Win7/Win8.1, Microsoft provided a more user-friendly downgrade option for this part of the user: the system rolled back. However, it should be noted that this "repentance medicine" function is "with shelf life" & rdquo;: can be used within one month after successful upgrade to Win10, expired. In other words, if you repent after a month, you can only use the traditional "simply rude" format to reload. In addition, you need to be reminded that if you want to repent after successfully upgrading Win10, Windows.old, which was previously reserved by Win7/Win8.1, must not be deleted. Because this is the root of “repentance medicine”, once you want to fall back to a lower version of Windows within a month, you must first ensure that the original operating system files actually exist. After the folder is deleted, it can only be downgraded to Win10 by formatting and reloading. If you meet the above two basic conditions that can downgrade Win10: 1 within a month 2 did not delete the Windows.old folder then you can use the Win10's own "rollback" function to achieve "peacedown". The specific method is as follows (return Win7/Win8.1 operation is the same, this article takes Win7 as an example): 1. Open the settings → update and security & rar; restore, find & ldquo; fall back to Windows7 (or Windows 8.1) ”, click “Start”. 2. Select “Retreat" Reasons (multiple choices), then click “Next”Continue (every step below can be cancelled at any time <; fallback & rdquo; operation). 3, carefully read the precautions, the whole process needs to have stable power support, which means that notebooks and tablets need to be retracted in the state of accessing the power cord, battery mode is not allowed; in addition, the system also prompted some Files and programs may be affected. Once you understand and take action, click “Next" to continue. 4. For users who have already set a login password, the password will be restored after the rollback, so you need to know the password to log in normally. After confirming that the message will not affect your use, click “Next” to continue. 5, the final step to confirm, remind Win7/Win8.1 users can upgrade to Win10 again at any time. In the future, the free installation of Win10 will no longer be subject to the time limit of “released within 1 year of the official version”, and is not subject to the installation method. Pure installation will also be completely free. 6. Click ““ to fall back to Windows7 (or Windows 8.1)”, the system will automatically restart and start the rollback process, which is time-consuming and directly related to the original system software installation and other use cases. The rolled-down Win7/Win8.1 system remains active.