After firewall-config is installed, it cannot be run, prompting (firewall-config:2222): Gtk-WARNING **:

[jlehtone]

As I wrote earlier, everything released since 7.9 has been bug (mostly security) fixes, because that is what RHEL Maintenance Phase means.
2013--2019 was the period, when RHEL 7 got "new bugs". 2019--2024 it is just kept running without affecting compatibility.

Another question: for the newly installed CentOS-7-x86_64-DVD-2009 system, that is, CentOS 7.9, after the installation and deployment is completed, is it necessary to run yum update to upgrade the system?

In other words, are there updates that are not included in the installer image?
The installer images are usually generated right after a point update is released, so any updates released after that cannot possibly be found from the image.

It is possible to give installer additional repos (other media or online). For example, to use also the updates repository that has those
"released for point update after the initial release of that point update" packages. You probably did not do that, and hence yes, you should run yum update.

[RedChimae]

As I wrote earlier, everything released since 7.9 has been bug (mostly security) fixes, because that is what RHEL Maintenance Phase means.
2013--2019 was the period, when RHEL 7 got "new bugs". 2019--2024 it is just kept running without affecting compatibility.

Another question: for the newly installed CentOS-7-x86_64-DVD-2009 system, that is, CentOS 7.9, after the installation and deployment is completed, is it necessary to run yum update to upgrade the system?

In other words, are there updates that are not included in the installer image?
The installer images are usually generated right after a point update is released, so any updates released after that cannot possibly be found from the image.

It is possible to give installer additional repos (other media or online). For example, to use also the updates repository that has those
"released for point update after the initial release of that point update" packages. You probably did not do that, and hence yes, you should run yum update.

Thank you so much! It has been successfully updated, and the kernel version has been upgraded from 3.10.0-1160.el7.x86_64 to 3.10.0-1160.95.1.el7.x86_64