Solution to the welcome to emergency mode message when booting CentOS7.4

Today I used a virtual machine to do an experiment. After the system was installed and some options were optimized, I mounted the ISO image file. After the system started, the following error was reported

I thought it was caused by mounting, and the original system entered the graphical interface after normal startup.

Sure enough, after I completed the mounting by mount /dev/cdrom/ /mnt/cdrom, I wrote a problem in /etc/fstab. A small mistake made the system like this. I can enter the password and then enter

There is a problem with the mount file that was written, and there is a problem with booting.

First delete this mount, then restart the system, the system starts normally.

It is recommended that you back up important configuration files before making changes. If problems occur, you can enter rescue mode and restore the original configuration.

The main operations are as follows:

First, enter the root password as prompted and log in to the rescue mode. Second, check the disk mount information. Third, comment out the content you added. If you are sure it is not in use, you can delete it. Fourth, restart OK.