Project scenario:

Install CentOS7.9 on the server, add an optical port card, add a network card and solve the problem
Job for network.service failed because the control process exited with error code problem

Problem Description

A problem was encountered in the actual project. The optical port card was pulled out from another server and plugged into the current server. The server is installed with the CentOS7.9 system. After the board is installed, you can see the interface information through ip addr:

But in the network card configuration, the network card cannot be seen, and the UUID query finds that there is no UUID information of the network card:

Most of the reasons for this phenomenon are that the device installed the operating system first, and then plugged in the network card. Here we can use the nmtui tool* (abbreviation for Network Manager Text User Interface, nmtui is a convenient tool that allows you to Use the graphical display in Linux server distributions to easily configure your network interfaces by calling the nmtui command directly from the terminal or even putty)*
Enter nmtui directly in the command:
1. Select Edit a connection
2. Select add (create)

3. Select Ethernet (Ethernet)

4. Enter the configuration file name and device name. These two names are consistent. Enter the name you see when you enter ip addr: enp2s0f0. After the input is completed, other options do not need to be configured. Move the cursor to the lower right corner, OK

5. After the creation is complete, you can see that the network card configuration has been added on the page of step 2, and select OK to return.

6. Back to the network card directory, you can find that the network card configuration file has been created, and a new UUID and MAC have been generated.


The information to add the network card here is actually over, but I reported an error during the process of restarting the network:
job for network.service failed because the control process exited with error code

Cause Analysis:

According to online information, it has been tested:
1. NetworkManager service-related issues
2. The configuration file MAC does not match the problem
3. Restart problem
I found that it was not working, so I checked the system log later: journalctl -xe (e: start from the end, x: related directory (such as the URL related to the problem))

It is found that there is no problem in starting the newly added network card, but there is a problem in starting the other network card. I remembered that I have copied the configuration of this network card before. The name of our new network card is: enp2s0f0, but the name of the network card that reported the error is: enp4s0f0.

solution:

Delete the error-reported network card file in the network-scripts directory, and restart the network card to return to normal! It is recommended that friends who have this problem first check the configuration file of the network card for simple spelling mistakes. If you do not check the system log, which network card failed to start and the network cannot be reset.