U盘安装centos7刚安装好时可以启动，重启一边后就启动不了了

系统是centos7，已装在U盘上了，第一次启动时可以启动但被我按了主机的重启键后再次启动就不行了，下面是提示的代码，求解！！！ generating "/run/initramfs/rdsosreport.txt" entering emergencymode.exit the shell to continue type "journalctl" to view system logs. you might want to save "/run/initramfs/rdsosreport.txt" to a usb stick or /boot after mounting them and attach it to a bug report

该用户不存在2