How To Fix Kubuntu 20.04 Plasma Desktop Not Starting After Login

In this article, we will provide a detailed guide on how to fix the issue of Kubuntu 20.04 Plasma Desktop not starting after login. This is a common problem that users might encounter, but with a few simple steps, you can troubleshoot and resolve this issue.

Introduction

Kubuntu is a free and open-source operating system based on the popular Ubuntu system. It uses the KDE Plasma Desktop instead of the GNOME desktop environment. Sometimes, users may find that the Plasma Desktop does not start after logging in. This can be due to various reasons such as system configuration issues, software conflicts, or bugs.

Solution 1: Resetting Plasma Desktop Configuration

The first solution involves resetting the Plasma Desktop configuration. This can be done by deleting the plasma-org.kde.plasma.desktop-appletsrc file. Here are the steps:

1. Press ALT+F2 to switch to the virtual console.
2. Login with your credentials.
3. Run the following commands:

sudo service sddm stop
rm ~/.config/plasma-org.kde.plasma.desktop-appletsrc
sudo service sddm start

The sudo service sddm stop command stops the Simple Desktop Display Manager (SDDM), which is the default display manager for KDE. The rm ~/.config/plasma-org.kde.plasma.desktop-appletsrc command deletes the Plasma Desktop configuration file. Finally, sudo service sddm start restarts the SDDM.

After running these commands, return to the desktop and check if the issue is resolved.

Solution 2: Kill SDDM Process

Another solution is to kill the SDDM process. This is particularly useful if the issue occurs while booting on battery power. Here’s how:

1. Press CTRL+ALT+F2 to access the console.
2. Run the following command: sudo killall sddm.

The sudo killall sddm command terminates all instances of the SDDM process.

Solution 3: Reconfigure SDDM

If you encounter a blank screen after the grub menu, you can try to reconfigure SDDM. Here are the steps:

1. Press CTRL+ALT+F2 to bring up the command line interface.
2. Run the following command: sudo dpkg-reconfigure sddm.

The sudo dpkg-reconfigure sddm command reconfigures the package sddm. After running this command, select gdm3 as the display manager and see if the issue is resolved.

Solution 4: Check Removable Devices Settings

If the issue is temporarily resolved by deleting the ~/.config/plasma-org.kde.plasma.desktop-appletsrc file, it may indicate a setting issue. You should check the “Removable Devices” settings:

1. Go to System Settings > Removable Devices.
2. Uncheck the option to automatically mount all removable media.
3. Instead, manually select the devices you want to mount at startup.

Solution 5: Switch Login Display Manager

If none of the above solutions work, you can try switching the login display manager:

1. Run the following command: sudo dpkg-reconfigure sddm.
2. Choose lightdm from the dropdown menu.

The lightdm is a cross-desktop display manager. After choosing lightdm, check if the login screen starts working. You can still choose the Plasma Desktop after entering your password.

Conclusion

In this article, we have discussed several solutions to fix the issue of Kubuntu 20.04 Plasma Desktop not starting after login. We hope that these solutions have helped you resolve the issue. Remember to back up any important data before making any changes to the system configuration. If you continue to experience problems, consider seeking help from the Kubuntu community.