症状

通过ssh能够登录omv，但通过web去访问，输入正确的用户名和密码后不能成功登录，查看详细信息，错误代码为

OMV\Rpc\Exception: Failed to connect to socket: No such file or directory 

处理过程

查看 /var/log/syslog 日志信息

nano /var/log/syslog

查看得到

'omv-engined' failed to start (exit status 1) -- '/bin/systemctl start openmediavault-engined'

尝试使用systemctl启动服务

systemctl start openmediavault-engined

报错，提示信息为

Failed to start openmediavault-engined.service: Unit openmediavault-engined.service is masked.

根据上述信息，执行下列命令

systemctl unmask openmediavault-engined.service
systemctl start openmediavault-engined

重新尝试登陆，成功