1. If possible, back up the system first. For specific backup operations, refer to https://support.apple.com/zh-cn/HT201250 . If there is any problem, please leave me a message
. 2. I am updating to macOS Sierra, so first Check to see if your device meets the requirements
2009 年末推出的 [MacBook](https://support.apple.com/zh-cn/HT201608) 或更新机型
2010 年末推出的 [MacBook Air](https://support.apple.com/zh-cn/HT201862) 或更新机型
2010 年中推出的 [MacBook Pro](https://support.apple.com/zh-cn/HT201300) 或更新机型
2010 年中推出的 [Mac mini](https://support.apple.com/zh-cn/HT201894) 或更新机型
2009 年末推出的 [iMac](https://support.apple.com/zh-cn/HT201634) 或更新机型
2010 年中推出的 [Mac Pro](https://support.apple.com/zh-cn/HT202888) 或更新机型
3. Download the macOS Sierra system (Mac needs to be equipped with at least 2 GB of memory and 8.8 GB of [available storage space]), the address is http://updates-http.cdn-apple.com/2019/cert/061-39476- 20191023-48f365f4-0015-4c41-9f44-39d3d2aca067/InstallOS.dmg
4. After the download is complete, double-click the downloaded file to open a window, and the content will be displayed in the window. Then double-click the file named "InstallOS.pkg" inside.
5. The instructions on the screen will guide you through the necessary installation steps, please follow the instructions.
6. Please do not put the Mac to sleep or close the lid to allow the installation to complete. When Mac is installing macOS and related updates of Mac firmware, it may restart multiple times, display a progress bar or display a blank screen. These are normal phenomena.
7. If you encounter any problems, you can leave me a message