想升级系统，然后发生如题错误，谷歌之，解决方法如下（希望帮助大家）：
Step 1. Go to your applications folder.
Step 2. Find the installer for macOS Sierra.
Step 3. Right click on the installer and click "Show Package Contents".
Step 4. Click on folder named "Contents".
Step 5. Click on the folder named "SharedSupport".
Step 6. Delete the file named "InstallInfo.plist".
Step 7. Enter your administer password to confirm.
Step 8. Now open the installer.
参考自苹果官网：https://discussions.apple.com/thread/7675283?start=0&tstart=0
PS：谷歌真好用