This error is because Shadowsocks has been installed on the computer and port 1087 is occupied. Just close and uninstall Shadowsocks.
If you confirm that SS has been uninstalled and the error still occurs, please follow the steps below:
1.Press the magnifying glass in the upper right corner, open Terminal, copy and paste and execute the following command:
pkill privoxy
rm -rf ~/Library/"Application Support"/ShadowsocksX-NG
2. Restart v2rayU