For Mac OS 10.11 and above, Apple introduced SIP (System Integrity Protection) under the core for the security of the system environment, also known as the Rootless mode mechanism. To upgrade or re-brush the device, the mechanism must be turned off to operate. Therefore, we must To turn off SIP.
Press and hold the ++command+R++ key to enter recovery mode. Or hold down the Option key and select
RecoveryHD in the boot selection menu that appears to enter recovery mode
Click Utilities > Click Terminal
Enter the command in the terminal:
csrutil disable and press Enter to execute, note that there is a space in the middle.
rebootin the terminal to restart the computer, or click the Apple logo and click Restart.
csrutil statusand press Enter
csrutil enableand press Enter.