[INF] install socat succeed...
Please enter your domain name: ###
[DEG] Your domain is: ###, checking it...
/usr/bin/x-ui: line 1117: /root/.acme.sh/acme.sh: No such file or directory
[INF] Your domain is ready for issuing certificates now...
Please choose which port to use (default is 80):
[ERR] Your input is invalid, will use default port ###.
[INF] Will use port: 80 to issue certificates. Please make sure this port is open.
/usr/bin/x-ui: line 1146: /root/.acme.sh/acme.sh: No such file or directory
/usr/bin/x-ui: line 1147: /root/.acme.sh/acme.sh: No such file or directory
[ERR] Issuing certificate failed, please check logs.
其实在你选择申请SSL证书的时候，他会自动安装Acme脚本，这个时候已经提示问题了
sudo apt install cron 安装一下就行了