What precautions should be taken post RHEL 8 to RHEL 9 upgrade using Leapp ?

Environment

• Red Hat Enterprise Linux 9.x
• Leapp

Issue

• System has RHEL 8 packages after Successful upgrade to RHEL 9.x.

# rpm -qa  | grep el8                        
kernel-4.18.0-513.9.1.el8_9.x86_64                                       
kernel-core-4.18.0-513.9.1.el8_9.x86_64                                    
kernel-devel-4.18.0-513.9.1.el8_9.x86_64                                    
kernel-modules-4.18.0-513.9.1.el8_9.x86_64                           
kernel-modules-extra-4.18.0-513.9.1.el8_9.x86_64           
kernel-workaround-0.1-1.el8.noarch                   
leapp-0.16.0-2.el8.noarch                        
leapp-upgrade-el8toel9-0.19.0-4.el8_9.noarch           
python3-leapp-0.16.0-2.el8.noarch                          

Resolution

1. Locate remaining RHEL 8 packages.

# rpm -qa | grep -e '\.el[78]' | grep -vE '^(gpg-pubkey|libmodulemd|katello-ca-consumer)' | sort

2. Remove remaining RHEL 8 packages from your RHEL 9 system.

# dnf remove $(rpm -qa | grep \.el[78] | grep -vE 'gpg-pubkey|libmodulemd|katello-ca-consumer')

3. Post upgrade to RHEL 9, make sure to perform all the steps mentioned in Performing post-upgrade tasks.

Root Cause

• Post leapp upgrade from RHEL 8 to RHEL 9 , few RHEL 8 or el8 packages were present on the system.
• After the in-place upgrade, RHEL 9 system must be cleaned up by removing unneeded packages, disabling incompatible repositories, and updating the rescue kernel and initial RAM disk.

Diagnostic Steps

• Verify if packages are installed of different major release

# rpm -qa | grep el8
kernel-4.18.0-513.9.1.el8_9.x86_64                                       
kernel-core-4.18.0-513.9.1.el8_9.x86_64                                    
kernel-devel-4.18.0-513.9.1.el8_9.x86_64                                    
kernel-modules-4.18.0-513.9.1.el8_9.x86_64                           
kernel-modules-extra-4.18.0-513.9.1.el8_9.x86_64           
kernel-workaround-0.1-1.el8.noarch                   
leapp-0.16.0-2.el8.noarch                        
leapp-upgrade-el8toel9-0.19.0-4.el8_9.noarch           
python3-leapp-0.16.0-2.el8.noarch                          

• Verify if RHEL 8 kernel modules or entries still exists.

# ls  /lib/modules   | grep el8
4.18.0-425.13.1.el8_7.x86_64
4.18.0-477.15.1.el8_8.x86_64
4.18.0-513.9.1.el8_9.x86_64 

# ls -l boot/loader/entries | grep el8
-rw-r--r--. 1 root root 622 Mar 22 21:24 xxxx-4.18.0-425.3.1.el8.x86_64.conf
-rw-r--r--. 1 root root 632 Mar 22 21:24 xxxx-4.18.0-513.9.1.el8_9.x86_64.conf

This solution is part of Red Hat’s fast-track publication program, providing a huge library of solutions that Red Hat engineers have created while supporting our customers. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.