Ubuntu gedit error: Failed to connect to the session manager

After su to root was used, the command gedit found an error: ** (gedit: 2976): WARNING **: the connection is closed (gedit: 2976 ): eggSMClient-WARNING **: Failed to connect to the session manager: None of the authentication protocols specified are supported ** (gedit: 2976): WARNING **: cocould not connect to session bus www.2cto.com: su can only switch to the administrator user permission, without the Administrator's login script and search path.
Su-not only can switch to administrator permissions, but also use the administrator login script and search path
Solution: After using sudo gedit or su-, there will be no error in gedit!