Unable to upgrade from RHEL6 to RHEL7

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Getting this error when running "preupg --riskcheck --verbose" command before upgrading.

preupg.risk.EXTREME: You have the GNOME desktop environment session as an option in your X11 session manager. The GNOME desktop environment as a part of the 'Desktop' yum group underwent a serious redesign in its user interface as well as in underlying technologies in Red Hat Enterprise Linux 7.
preupg.risk.EXTREME: You have the KDE desktop environment session as an option in your X11 session manager. The KDE desktop environment as a part of the yum group 'KDE Desktop' underwent a redesign in its user interface as well as in underlying technologies in Red Hat Enterprise Linux 7.

I've tried removing both KDE and Gnome through yum. Even after removing them the preupg check still gives me the same error message. So I tried rebooting and then the system just froze when it tried to restart. Guessing something is trying to launch the desktop environment and there is no longer anything there to run. It just freezes solid and I'm unable to even ping or ssh to the server.

Any advice appreciated.


Hi Jay,

Upgrading from one major release to the next might work (in some ways) or not - but it is definitely not recommended.
You would have to expect serious problems and issues being hidden under the hood which may appear sooner or later.
Especially when you have additional desktop environments in use ... please perform a fresh installation of RHEL 7.6 ! :)


Hi Jay,

Roll back server to pre-upgrade state (if possible). In-place upgrade of RHEL 6 to 7 with GNOME/KDE is not recommended.

Regarding preupg errors, KB976053 advises switching to runlevel 3, remove desktop environment packages then retry upgrade with redhat-upgrade-tool. Upgrading from RHEL 6 to RHEL 7 on Gnome Desktop Environment failed

Thanks guys. With all the issues found in the preupgrade tool, I'm pretty convinced at this point you both are right. I did find the --force command when running the redhat-upgrade-tool command that will go ahead and force the upgrade despite the recommendations of the preupg tool. I'm trying it on a cloned test system atm and will see how that works out. I figure probably not well, but can't hurt to see how it works out for the time being. Thanks much for the responses.


You're welcome, Jay ! Forcing the upgrade might make things even worse ... but well, just for testing that'd be okay. :)


So Jay, (or anyone landing here)

Make sure to totally back up all data you care about on the server in a rational way so that if this goes poorly, you can build a current Red Hat system and restore it with the data you have. RHEL 6 expires in 2020 (Red Hat 6 expires without extended support in November 2020, RHEL 7 in 2024). Of course that's why you're attempting an upgrade. However, it is pretty risky to do this kind of upgrade.

Also, seriously consider building a Red Hat 7 system from scratch because while you can ... possibly go from RHEL 6 to 7 using the upgrade method, it is messy, unreliable, and with a workstation will likely go very poorly.

wish you well



I am wondering whether Upgrade is a valid term when it comes to moving from RHEL6 to RHEL7 since both releases have really nothing in common. Considering the fact that so many configuration files, filesystems structure and commands are completely different. This is my personal opinion. I sincerely believe that the safest way to achieve this is to follow Jay's suggestion. My question is how do we then move important data from the old server to the new one with the same IP address after a new one has been built?

Hi All,

My apologies for not updating this back in April/May of last year. I was able to successfully upgrade a few test systems from 6 to 7. I have the procedure documented and will link it below. Please note however we decided to be on the safe side and just setup a new RHEL 7 server and migrate the data over to it as we didn't want to risk any unseen issues that may have eventually cropped up as a result of the upgrade. However saying that, I wasn't getting any errors in anything after I finally got it to upgrade. It was booting fine with no errors. Yum worked perfectly with no errors as well. It was quite a few steps involved and would probably be faster in most cases to just spin up a new server and migrate, but if this information is valuable to anyone, you are welcome to use it by all means. Just thread cautiously as it hasn't been tested to really see if it will work in all capacities at 100% after the upgrade. To the eye, everything seemed to have been successful, but keep in mind we never ran anything in production on the upgraded systems

Also please pardon my lack of linux knowledge if there are easier steps to do what I have listed in the documentation. It had been almost 4 years since I had to deal with linux on a day to day basis and I was having to relearn many things all over again or for the first time. :)