Yesterday I upgraded Fedora 24 to 25 reading below article that I used last time. 
Unfortunately I have faced several issues after that. I want to take note for that here.
There are some articles about Upgrading Fedora . Later I want to check these articles.
But today I want to write especially about a issue “Can not boot”, that I solved today.
The situation is
I have used official docker RPM package (package name is
Because the Fedora docker RPM package (package name is
docker) is older version. It is Fedora official, but unofficial package for the vendor Docker. I could not use some new features.
$ sudo dnf remove docker-engine
Then I got an error.
$ sudo dnf install docker ... Failed to obtain the transaction lock (logged in as: root) ...
The solution was .
In my case with same problem is solved by doing following steps: 1. dnf clean all 2. Restart the system.
However I restarted the system. It started and freezed in login processing page.
I typed “Ctrl, Alt + BS key” to change to CUI console.
And I got below error.
[!!!!!!] Failed to load SELinux policy, freezing.
I needed to login with single user mode, and SELinux off.
Seeing this article , ran below operations.
One possibility for that issue is from upgrading to 25. And saw article . Then ran, and rebooted. And still does not work.
$ sudo touch /.autorelabel
# vi /etc/sysconfig/selinux SELINUX=enforcing => SELINUX=disabled
-  Upgrading Fedora 23 Workstation to Fedora 24 - Fedora Magazine
-  https://fedoraproject.org/wiki/DNF_system_upgrade#Resolving_post-upgrade_issues
-  Common F25 bugs - FedoraProject
-  How to boot into 'single user mode' in Fedora 20 - Quora