Charles cannot configure your proxy settings while it is on a read-only volume. Perhaps you are running Charles from the disk image? If so, please copy Charles to the Applications folder and run it again. Otherwise please ensure that Charles is writable by the current user and try again.
 解决：

终端输入后重启

sudo chown -R root "/Applications/Charles.app/Contents/Resources"
sudo chmod -R u+s "/Applications/Charles.app/Contents/Resources"