How to fix Kernel after a dnf installation

To get the index number of all the installed kernels:

  sudo grubby --info=ALL | grep -E "^kernel|^index"

The output should be something like this:

 index=0
 kernel="/boot/vmlinuz-5.15.10-200.fc35.x86_64"
 index=1
 kernel="/boot/vmlinuz-5.15.10-lqx1.0.fc35.x86_64"
 index=2
 kernel="/boot/vmlinuz-5.15.8-200.fc35.x86_64"
 index=3
 kernel="/boot/vmlinuz-5.15.8-lqx1.0.fc35.x86_64"


Now we can change the default kernel by using the index number:

 sudo grubby --set-default-index=1


Verify that the right kernel has been set as default:

   sudo grubby --default-title

The output will be the default kernel title:

 Fedora Linux (5.15.10-lqx1.0.fc35.x86_64) 35 (Workstation Edition)
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