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Chapter 6. Verifying the post-upgrade state of the RHEL 9 system

This procedure lists verification steps recommended to perform after an in-place upgrade to RHEL 9.

Prerequisites

The system has been upgraded following the steps described in Performing the upgrade from RHEL 8 to RHEL 9 and you have been able to log in to RHEL 9.

Procedure

After the upgrade completes, determine whether the system is in the required state, at least:

Verify that the current OS version is RHEL 9. For example:

# cat /etc/redhat-release
Red Hat Enterprise Linux release 9.0 (Plow)

Check the OS kernel version. For example:
```
# uname -r
5.14.0-70.10.1.el9_0.x86_64
```
Note that .el9 is important and the version should not be earlier than 5.14.0.

If you are using the Red Hat Subscription Manager:

Verify that the correct product is installed. For example:

# subscription-manager list --installed
+-----------------------------------------+
    	  Installed Product Status
+-----------------------------------------+
Product Name: Red Hat Enterprise Linux for x86_64
Product ID:   479
Version:      9.0
Arch:         x86_64
Status:       Subscribed

Verify that the release version is set to the expected target OS version immediately after the upgrade. For example:
```
# subscription-manager release
Release: 9.0
```

Verify that network services are operational, for example, try to connect to a server using SSH.
Check the post-upgrade status of your applications. In some cases, you may need to perform migration and configuration changes manually. For example, to migrate your databases, follow instructions in Configuring and using database servers.