1. obs studio 窗口采集需要 x11在 Wayland无 GNU下无效2, Ubuntu 24.04 默认 Wayland。简单修改 /etc/gdm3/custom.conf ubuntu24.04桌面环境切换Wayland为X11_ubuntu wayland x11-CSDN博客 后切换到 x11后鼠标异常。3.GNOME X11 REMOVALGNOME X11 sessions cannot be restored on Ubuntu 26.04. The X11 code wascompletely removedfrom GNOME 49 upstream, making it impossible to run GNOME Shell on X11 regardless of Xorg installation.How to Install X11 on Ubuntu 26.049 February 2026 by Lubos RendekHow to Install X11 on Ubuntu 26.04Ubuntu 26.04 marks a significant shift in display server technology, with Wayland becoming the exclusive default for major desktop environments. While this transition brings enhanced security and performance, some users require X11 (also known as X.Org or Xorg) for specific applications, hardware compatibility, or remote desktop workflows. This comprehensive guide shows you how to install x11 ubuntu 26.04, configure desktop-specific X11 sessions, and switch between display servers as needed.Table of Contents→ Understanding the X11 Change→ Base Xorg Installation→ Desktop Environment X11 Sessions→ Verifying Your Display Server→ Switching Between X11 and Wayland→ Troubleshooting→ FAQIn this tutorial you will learn:Why X11 is no longer included by defaultHow to install base Xorg packagesDesktop-specific X11 session installationHow to verify your current display serverHow to switch between X11 and Wayland sessionsInstalling X11 display server on Ubuntu 26.04Software RequirementsSoftware Requirements and Linux Command Line ConventionsCategoryRequirements, Conventions or Software Version UsedSystemUbuntu 26.04 Resolute RaccoonSoftwareX.Org Server 21.x (available from Ubuntu repositories)OtherPrivileged access to your Linux system as root or via thesudocommand.Conventions#– requires given linux commands to be executed with root privileges either directly as a root user or by use ofsudocommand$– requires given linux commands to be executed as a regular non-privileged userTL;DRInstall X11 on Ubuntu 26.04 by installing base Xorg packages and optional desktop-specific X11 sessions, then select the X11 session at your login screen.Quick Steps to Install X11StepCommand/Action1. Update system packagessudo apt update2. Install base Xorgsudo apt install xorg -y3. Install desktop X11 session (KDE example)sudo apt install plasma-session-x11 -y4. Reboot and select X11 session at loginsudo rebootUnderstanding the X11 Change in Ubuntu 26.04Ubuntu 26.04 represents a pivotal moment in Linux desktop evolution. The distribution has transitioned to Wayland as the exclusive display server for major desktop environments, specifically GNOME and KDE Plasma. This change reflects broader industry trends toward modern display server technology.Why X11 Was RemovedStarting with Ubuntu 25.10, Canonical made the strategic decision to remove X11 sessions from default installations. This decision was driven by upstream projects: GNOME completely removed X11 support code in GNOME 49, while KDE Plasma no longer includes X11 sessions by default. Consequently, fresh installations of Ubuntu 26.04 ship exclusively with Wayland sessions.The reasons behind this transition include improved security architecture, better support for modern hardware features like high-DPI displays and multi-monitor setups, reduced input latency, and streamlined development focus. Wayland’s design addresses fundamental security limitations in X11’s architecture, where any application could monitor keystrokes from other applications.When You Need X11Despite Wayland’s advantages, several scenarios still require X11:Legacy applications:Some older software lacks Wayland support and doesn’t function properly through XWayland compatibility layerRemote desktop solutions:Certain remote access tools work exclusively with X11Screen recording and automation:Some specialized tools require direct X11 accessHardware compatibility:Older graphics drivers may have better X11 supportDevelopment and testing:Developers maintaining X11 applications need native X11 environmentsWAYLAND COMPATIBILITYMost modern applications run seamlessly on Wayland through XWayland, which provides X11 application compatibility. Test your critical applications on Wayland first before installing X11, as you may not need it.Base Xorg InstallationThe X.Org Server remains available in Ubuntu 26.04 repositories. Installing the base Xorg package provides the foundational X11 display server components needed for any X11 session.Installing Core Xorg PackagesFirst, ensure your system package list is current:$ sudo apt updateThen install the Xorg server and essential components:$ sudo apt install xorg -yThis command installs the X.Org X Window System, including the X server, video drivers, input device drivers, and fundamental X11 libraries. The installation typically downloads approximately 150-200MB of packages and requires about 500MB of disk space.Thexorgmetapackage includes:xserver-xorg-core:The core X11 serverxserver-xorg-video-*:Video drivers for various graphics hardwarexserver-xorg-input-*:Input device drivers for keyboards, mice, and touchpadsx11-xserver-utils:Essential X11 utilities like xrandr and xsetrootAdditional X11 UtilitiesFor a more complete X11 environment, consider installing additional utility packages:$ sudo apt install x11-apps x11-utils -yThese packages provide useful tools for testing and managing your X11 environment:x11-apps:Basic X applications like xclock, xeyes, and xlogo for testingx11-utils:Diagnostic utilities including xdpyinfo, xwininfo, and xpropDesktop Environment X11 SessionsAfter installing base Xorg packages, you need desktop-specific X11 session files to actually use X11 with your desktop environment. Requirements vary significantly between desktop environments.KDE Plasma X11 SessionKDE Plasma supports X11 but doesn’t include it by default in Ubuntu 26.04. Install the X11 session package separately:$ sudo apt install plasma-session-x11 -yThis package provides the “Plasma (X11)” session option at the SDDM login screen. After installation and reboot, you can select between “Plasma (Wayland)” and “Plasma (X11)” sessions.KDE X11 DEPRECATIONKDE plans to remove X11 support entirely in Plasma 6.8 (expected late 2026). The X11 session is maintained for compatibility but receives limited development focus.GNOME X11 SessionGNOME presents a different situation. The GNOME project completely removed X11 support code from GNOME 49 (shipped in Ubuntu 25.10 and later). Therefore,GNOME X11 sessions cannot be installed on Ubuntu 26.04regardless of Xorg installation.Users requiring GNOME with X11 have two options:Continue using Ubuntu 24.04 LTS, which includes GNOME X11 sessions and receives support until 2029Switch to an alternative desktop environment that maintains X11 supportAlternative Desktop Environments with Built-in X11Several desktop environments continue supporting X11 as their primary or co-equal display server. These environments include X11 support automatically when installed:Xfce DesktopXfce remains primarily X11-focused with excellent stability:$ sudo apt install xfce4 xfce4-goodies -yXfce provides a lightweight, traditional desktop experience with comprehensive X11 support. The desktop environment works reliably with older hardware and maintains excellent performance.MATE DesktopMATE, a GNOME 2 fork, continues prioritizing X11 support:$ sudo apt install ubuntu-mate-desktop -yMATE offers a classic desktop layout familiar to users of older GNOME versions. The environment has begun Wayland development but maintains X11 as the primary focus.Cinnamon DesktopCinnamon, Linux Mint’s flagship desktop, remains X11-native:$ sudo apt install cinnamon-desktop-environment -yCinnamon provides a modern, elegant interface while maintaining full X11 compatibility. The development team is working toward Wayland support but hasn’t set a firm timeline for transition.LXQt DesktopLXQt offers a lightweight Qt-based desktop with X11 support:$ sudo apt install lxqt -yLXQt focuses on resource efficiency while providing a complete desktop environment. It works particularly well on older hardware or systems with limited resources.Session selector showing available desktop environments including both Wayland and X11 optionsVerifying Your Display ServerAfter installing X11 and rebooting, verify which display server your current session uses.Checking Current Session TypeThe simplest verification method uses an environment variable:$ echo $XDG_SESSION_TYPEThis command returns eitherx11orwayland, indicating your current session’s display server.Example output for X11 session:x11Example output for Wayland session:waylandDetailed Session InformationFor more comprehensive session details, use theloginctlcommand:$ loginctl show-session $(loginctl | grep $(whoami) | awk {print $1}) -p TypeThis command displays the session type property from systemd’s login manager.Verifying Xorg ProcessWhen running an X11 session, the Xorg server process should be active:$ ps aux | grep XorgLook for a running Xorg process. If you see the Xorg process with various parameters, your X11 server is running successfully.Terminal output confirming X11 display server is activeSwitching Between X11 and WaylandUbuntu 26.04 allows switching between X11 and Wayland sessions at login, provided both are installed and your desktop environment supports both protocols.Selecting Session at LoginThe session selection process occurs at your display manager (login screen):Log out of your current session: Click your system menu and select “Log Out” to return to the login screenAccess session selection: At the login screen, click your username to reveal the password field. Before entering your password, locate the session selector icon (typically a gear icon or session name) in the corner of the screenChoose your session: Click the session selector to display available options. For KDE Plasma, you’ll see:Plasma (Wayland)– Default Wayland sessionPlasma (X11)– X11 session (if plasma-session-x11 installed)For Xfce, MATE, Cinnamon, or LXQt, the standard session uses X11 by defaultLog in: After selecting your preferred session, enter your password and log in. The display manager remembers your selection for future loginsDisplay Manager DifferencesDifferent display managers present session selection slightly differently:SDDM (KDE Plasma):Session selector appears as “Desktop Session” in the bottom-left cornerGDM3 (GNOME/Ubuntu):Gear icon appears near the “Sign In” buttonLightDM (Xfce, MATE):Session dropdown menu typically appears at the top of the login screenMaking X11 Permanent DefaultYour session selection persists automatically across reboots. To ensure X11 remains the default, simply select the X11 session once at login. The display manager stores this preference and uses it for all subsequent logins until you manually change it again.Xfce desktop environment running on X11 windowing system on Ubuntu 26.04Troubleshooting Common IssuesWhen installing or using X11 on Ubuntu 26.04, you may encounter various issues. Here are solutions to common problems.X11 Session Not Appearing at LoginIf the X11 session option doesn’t appear after installation, verify the session file exists:$ ls /usr/share/xsessions/For KDE Plasma, look forplasmax11.desktop. If missing, reinstall the session package:$ sudo apt install --reinstall plasma-session-x11Then restart your display manager:$ sudo systemctl restart sddm(Replacesddmwithgdm3orlightdmdepending on your display manager)Black Screen After Selecting X11 SessionA black screen typically indicates video driver issues. First, try switching to a text console (CtrlAltF3) and check Xorg logs:$ cat /var/log/Xorg.0.log | grep EEThe output shows error messages (marked with “EE”) that indicate the problem. Common causes include:Missing video drivers:Install appropriate drivers for your graphics hardwareConfiguration conflicts:Remove or backup/etc/X11/xorg.confif it existsInsufficient permissions:Ensure your user belongs to thevideogroupTo add your user to the video group:$ sudo usermod -a -G video $USERLog out and back in for the change to take effect.GNOME Not Offering X11 SessionAs mentioned earlier, GNOME completely removed X11 support. If you require GNOME with X11:Use Ubuntu 24.04 LTS, which includes GNOME X11 sessionsSwitch to a different desktop environment that supports X11Continue using GNOME on Wayland and report compatibility issues to application developersGNOME X11 REMOVALGNOME X11 sessions cannot be restored on Ubuntu 26.04. The X11 code was completely removed from GNOME 49 upstream, making it impossible to run GNOME Shell on X11 regardless of Xorg installation.Applications Not Starting Under X11Some applications may fail to start in X11 sessions due to Wayland-specific dependencies. Check application output for errors:$ application-name 21 | grep -i displayIf the application expects Wayland, you may need to:Check for X11-compatible versions or flagsInstall X11-specific packages (e.g.,qt5-x11extrasfor Qt applications)Set theQT_QPA_PLATFORMxcbenvironment variable for Qt applicationsPoor Performance or TearingIf you experience screen tearing or poor performance under X11:First, enable the compositor if your desktop environment has one disabled. For Xfce:$ xfconf-query -c xfwm4 -p /general/use_compositing -s trueFor environments using Compton/Picom, install and configure it:$ sudo apt install picom -yAdditionally, verify that your graphics drivers are properly installed and configured. Proprietary drivers often provide better performance than open-source alternatives for NVIDIA hardware.Package Conflict: libpeas During Desktop Environment InstallationWhen installing desktop environments like Cinnamon, MATE, or Xfce, you may encounter a package conflict error with libpeas:dpkg: error processing archive /var/cache/apt/archives/libpeas-1.0-1_1.38.1-1_amd64.deb (--unpack): trying to overwrite /usr/lib/x86_64-linux-gnu/libpeas-1.0/loaders/libpython3loader.so, which is also in package libpeas-1.0-0:amd64This error occurs when transitioning between libpeas package versions, where both the old (libpeas-1.0-0) and new (libpeas-1.0-1) versions contain the same file. The package manager cannot proceed because it would overwrite an existing file.To resolve this conflict, force dpkg to overwrite the conflicting file:$ sudo dpkg -i --force-overwrite /var/cache/apt/archives/libpeas-1.0-1_1.38.1-1_amd64.deb $ sudo apt --fix-broken installThe first command forces installation of the new package version, overwriting the conflicting file. The second command resolves any remaining dependency issues and completes the installation. After these commands complete successfully, your desktop environment installation will proceed normally.PACKAGE CONFLICTSPackage conflicts during Ubuntu 26.04’s development cycle are not uncommon as packages transition between versions. The--force-overwriteflag should only be used when you understand the conflict involves identical files from different package versions.ConclusionInstalling X11 on Ubuntu 26.04 requires understanding the display server landscape changes and taking deliberate installation steps. While Wayland represents the future of Linux graphics, X11 remains available for users who need it for compatibility, specific applications, or hardware requirements. By installing base Xorg packages and desktop-specific X11 sessions, you can maintain access to traditional X11 functionality alongside modern Wayland capabilities.Remember that X11 support is gradually diminishing across the Linux ecosystem. KDE Plasma plans to remove X11 in version 6.8, and GNOME has already completed its transition. Therefore, treat X11 as a transitional solution while working toward Wayland compatibility for your workflows. For more information about X11 and Xorg configuration, consult the official X.Org Foundation documentation.Frequently Asked QuestionsCan I install GNOME with X11 on Ubuntu 26.04?No, GNOME completely removed X11 support code in GNOME 49, which ships with Ubuntu 26.04. There is no way to restore GNOME X11 sessions on Ubuntu 26.04. Users requiring GNOME with X11 should use Ubuntu 24.04 LTS, which maintains GNOME X11 sessions until 2029, or switch to alternative desktop environments like Xfce, MATE, or Cinnamon that continue supporting X11.Will installing X11 affect my existing Wayland session?No, installing X11 does not affect or interfere with Wayland sessions. Both display servers can coexist on the same system, and you can freely switch between them at login. Your desktop environment, applications, and settings remain separate for each session type, allowing you to use whichever works best for specific tasks or applications.How do I know if I’m currently using X11 or Wayland?Run the commandecho $XDG_SESSION_TYPEin a terminal. It will return either “x11” or “wayland” indicating your current display server. You can also check by runningloginctl show-session $(loginctl | grep $(whoami) | awk {print $1}) -p Typefor more detailed session information from systemd’s login manager.Which desktop environments still support X11 in Ubuntu 26.04?Xfce, MATE, Cinnamon, and LXQt all maintain full X11 support and include it by default when installed. KDE Plasma supports X11 through an optional package (plasma-session-x11) but plans to remove support in Plasma 6.8. GNOME has completely removed X11 support and cannot run X11 sessions on Ubuntu 26.04 or later versions.Is X11 being completely removed from Ubuntu?No, the Xorg packages remain available in Ubuntu repositories. What has changed is that X11 sessions are no longer installed or configured by default for major desktop environments. Users who need X11 can still install it manually. However, upstream desktop environment projects are gradually phasing out X11 support, so long-term availability depends on those upstream decisions rather than Ubuntu itself.Related Posts:Wayland Display Server Guide on Ubuntu 26.04Ubuntu Wayland: Enable and Disable GuideHow to Disable Wayland on Ubuntu 26.04Ubuntu 26.04: Release Date and New Features in…How to Change Default Desktop Environment on Ubuntu 26.04Ultimate Web Server Benchmark: Apache, NGINX,…Categories System AdministrationHow to Install KDE Plasma on Ubuntu 26.04How to Install Xfce on Ubuntu 26.04 
长河君 · 2026/8/23 8:44:56 · 阅读 1.2k How to Install X11 on Ubuntu 26.04；obs studio 窗口采集失效
1. obs studio 窗口采集需要 x11在 Wayland无 GNU下无效2, Ubuntu 24.04 默认 Wayland。简单修改 /etc/gdm3/custom.conf ubuntu24.04桌面环境切换Wayland为X11_ubuntu wayland x11-CSDN博客 后切换到 x11后鼠标异常。3.GNOME X11 REMOVALGNOME X11 sessions cannot be restored on Ubuntu 26.04. The X11 code wascompletely removedfrom GNOME 49 upstream, making it impossible to run GNOME Shell on X11 regardless of Xorg installation.How to Install X11 on Ubuntu 26.049 February 2026 by Lubos RendekHow to Install X11 on Ubuntu 26.04Ubuntu 26.04 marks a significant shift in display server technology, with Wayland becoming the exclusive default for major desktop environments. While this transition brings enhanced security and performance, some users require X11 (also known as X.Org or Xorg) for specific applications, hardware compatibility, or remote desktop workflows. This comprehensive guide shows you how to install x11 ubuntu 26.04, configure desktop-specific X11 sessions, and switch between display servers as needed.Table of Contents→ Understanding the X11 Change→ Base Xorg Installation→ Desktop Environment X11 Sessions→ Verifying Your Display Server→ Switching Between X11 and Wayland→ Troubleshooting→ FAQIn this tutorial you will learn:Why X11 is no longer included by defaultHow to install base Xorg packagesDesktop-specific X11 session installationHow to verify your current display serverHow to switch between X11 and Wayland sessionsInstalling X11 display server on Ubuntu 26.04Software RequirementsSoftware Requirements and Linux Command Line ConventionsCategoryRequirements, Conventions or Software Version UsedSystemUbuntu 26.04 Resolute RaccoonSoftwareX.Org Server 21.x (available from Ubuntu repositories)OtherPrivileged access to your Linux system as root or via thesudocommand.Conventions#– requires given linux commands to be executed with root privileges either directly as a root user or by use ofsudocommand$– requires given linux commands to be executed as a regular non-privileged userTL;DRInstall X11 on Ubuntu 26.04 by installing base Xorg packages and optional desktop-specific X11 sessions, then select the X11 session at your login screen.Quick Steps to Install X11StepCommand/Action1. Update system packagessudo apt update2. Install base Xorgsudo apt install xorg -y3. Install desktop X11 session (KDE example)sudo apt install plasma-session-x11 -y4. Reboot and select X11 session at loginsudo rebootUnderstanding the X11 Change in Ubuntu 26.04Ubuntu 26.04 represents a pivotal moment in Linux desktop evolution. The distribution has transitioned to Wayland as the exclusive display server for major desktop environments, specifically GNOME and KDE Plasma. This change reflects broader industry trends toward modern display server technology.Why X11 Was RemovedStarting with Ubuntu 25.10, Canonical made the strategic decision to remove X11 sessions from default installations. This decision was driven by upstream projects: GNOME completely removed X11 support code in GNOME 49, while KDE Plasma no longer includes X11 sessions by default. Consequently, fresh installations of Ubuntu 26.04 ship exclusively with Wayland sessions.The reasons behind this transition include improved security architecture, better support for modern hardware features like high-DPI displays and multi-monitor setups, reduced input latency, and streamlined development focus. Wayland’s design addresses fundamental security limitations in X11’s architecture, where any application could monitor keystrokes from other applications.When You Need X11Despite Wayland’s advantages, several scenarios still require X11:Legacy applications:Some older software lacks Wayland support and doesn’t function properly through XWayland compatibility layerRemote desktop solutions:Certain remote access tools work exclusively with X11Screen recording and automation:Some specialized tools require direct X11 accessHardware compatibility:Older graphics drivers may have better X11 supportDevelopment and testing:Developers maintaining X11 applications need native X11 environmentsWAYLAND COMPATIBILITYMost modern applications run seamlessly on Wayland through XWayland, which provides X11 application compatibility. Test your critical applications on Wayland first before installing X11, as you may not need it.Base Xorg InstallationThe X.Org Server remains available in Ubuntu 26.04 repositories. Installing the base Xorg package provides the foundational X11 display server components needed for any X11 session.Installing Core Xorg PackagesFirst, ensure your system package list is current:$ sudo apt updateThen install the Xorg server and essential components:$ sudo apt install xorg -yThis command installs the X.Org X Window System, including the X server, video drivers, input device drivers, and fundamental X11 libraries. The installation typically downloads approximately 150-200MB of packages and requires about 500MB of disk space.Thexorgmetapackage includes:xserver-xorg-core:The core X11 serverxserver-xorg-video-*:Video drivers for various graphics hardwarexserver-xorg-input-*:Input device drivers for keyboards, mice, and touchpadsx11-xserver-utils:Essential X11 utilities like xrandr and xsetrootAdditional X11 UtilitiesFor a more complete X11 environment, consider installing additional utility packages:$ sudo apt install x11-apps x11-utils -yThese packages provide useful tools for testing and managing your X11 environment:x11-apps:Basic X applications like xclock, xeyes, and xlogo for testingx11-utils:Diagnostic utilities including xdpyinfo, xwininfo, and xpropDesktop Environment X11 SessionsAfter installing base Xorg packages, you need desktop-specific X11 session files to actually use X11 with your desktop environment. Requirements vary significantly between desktop environments.KDE Plasma X11 SessionKDE Plasma supports X11 but doesn’t include it by default in Ubuntu 26.04. Install the X11 session package separately:$ sudo apt install plasma-session-x11 -yThis package provides the “Plasma (X11)” session option at the SDDM login screen. After installation and reboot, you can select between “Plasma (Wayland)” and “Plasma (X11)” sessions.KDE X11 DEPRECATIONKDE plans to remove X11 support entirely in Plasma 6.8 (expected late 2026). The X11 session is maintained for compatibility but receives limited development focus.GNOME X11 SessionGNOME presents a different situation. The GNOME project completely removed X11 support code from GNOME 49 (shipped in Ubuntu 25.10 and later). Therefore,GNOME X11 sessions cannot be installed on Ubuntu 26.04regardless of Xorg installation.Users requiring GNOME with X11 have two options:Continue using Ubuntu 24.04 LTS, which includes GNOME X11 sessions and receives support until 2029Switch to an alternative desktop environment that maintains X11 supportAlternative Desktop Environments with Built-in X11Several desktop environments continue supporting X11 as their primary or co-equal display server. These environments include X11 support automatically when installed:Xfce DesktopXfce remains primarily X11-focused with excellent stability:$ sudo apt install xfce4 xfce4-goodies -yXfce provides a lightweight, traditional desktop experience with comprehensive X11 support. The desktop environment works reliably with older hardware and maintains excellent performance.MATE DesktopMATE, a GNOME 2 fork, continues prioritizing X11 support:$ sudo apt install ubuntu-mate-desktop -yMATE offers a classic desktop layout familiar to users of older GNOME versions. The environment has begun Wayland development but maintains X11 as the primary focus.Cinnamon DesktopCinnamon, Linux Mint’s flagship desktop, remains X11-native:$ sudo apt install cinnamon-desktop-environment -yCinnamon provides a modern, elegant interface while maintaining full X11 compatibility. The development team is working toward Wayland support but hasn’t set a firm timeline for transition.LXQt DesktopLXQt offers a lightweight Qt-based desktop with X11 support:$ sudo apt install lxqt -yLXQt focuses on resource efficiency while providing a complete desktop environment. It works particularly well on older hardware or systems with limited resources.Session selector showing available desktop environments including both Wayland and X11 optionsVerifying Your Display ServerAfter installing X11 and rebooting, verify which display server your current session uses.Checking Current Session TypeThe simplest verification method uses an environment variable:$ echo $XDG_SESSION_TYPEThis command returns eitherx11orwayland, indicating your current session’s display server.Example output for X11 session:x11Example output for Wayland session:waylandDetailed Session InformationFor more comprehensive session details, use theloginctlcommand:$ loginctl show-session $(loginctl | grep $(whoami) | awk {print $1}) -p TypeThis command displays the session type property from systemd’s login manager.Verifying Xorg ProcessWhen running an X11 session, the Xorg server process should be active:$ ps aux | grep XorgLook for a running Xorg process. If you see the Xorg process with various parameters, your X11 server is running successfully.Terminal output confirming X11 display server is activeSwitching Between X11 and WaylandUbuntu 26.04 allows switching between X11 and Wayland sessions at login, provided both are installed and your desktop environment supports both protocols.Selecting Session at LoginThe session selection process occurs at your display manager (login screen):Log out of your current session: Click your system menu and select “Log Out” to return to the login screenAccess session selection: At the login screen, click your username to reveal the password field. Before entering your password, locate the session selector icon (typically a gear icon or session name) in the corner of the screenChoose your session: Click the session selector to display available options. For KDE Plasma, you’ll see:Plasma (Wayland)– Default Wayland sessionPlasma (X11)– X11 session (if plasma-session-x11 installed)For Xfce, MATE, Cinnamon, or LXQt, the standard session uses X11 by defaultLog in: After selecting your preferred session, enter your password and log in. The display manager remembers your selection for future loginsDisplay Manager DifferencesDifferent display managers present session selection slightly differently:SDDM (KDE Plasma):Session selector appears as “Desktop Session” in the bottom-left cornerGDM3 (GNOME/Ubuntu):Gear icon appears near the “Sign In” buttonLightDM (Xfce, MATE):Session dropdown menu typically appears at the top of the login screenMaking X11 Permanent DefaultYour session selection persists automatically across reboots. To ensure X11 remains the default, simply select the X11 session once at login. The display manager stores this preference and uses it for all subsequent logins until you manually change it again.Xfce desktop environment running on X11 windowing system on Ubuntu 26.04Troubleshooting Common IssuesWhen installing or using X11 on Ubuntu 26.04, you may encounter various issues. Here are solutions to common problems.X11 Session Not Appearing at LoginIf the X11 session option doesn’t appear after installation, verify the session file exists:$ ls /usr/share/xsessions/For KDE Plasma, look forplasmax11.desktop. If missing, reinstall the session package:$ sudo apt install --reinstall plasma-session-x11Then restart your display manager:$ sudo systemctl restart sddm(Replacesddmwithgdm3orlightdmdepending on your display manager)Black Screen After Selecting X11 SessionA black screen typically indicates video driver issues. First, try switching to a text console (CtrlAltF3) and check Xorg logs:$ cat /var/log/Xorg.0.log | grep EEThe output shows error messages (marked with “EE”) that indicate the problem. Common causes include:Missing video drivers:Install appropriate drivers for your graphics hardwareConfiguration conflicts:Remove or backup/etc/X11/xorg.confif it existsInsufficient permissions:Ensure your user belongs to thevideogroupTo add your user to the video group:$ sudo usermod -a -G video $USERLog out and back in for the change to take effect.GNOME Not Offering X11 SessionAs mentioned earlier, GNOME completely removed X11 support. If you require GNOME with X11:Use Ubuntu 24.04 LTS, which includes GNOME X11 sessionsSwitch to a different desktop environment that supports X11Continue using GNOME on Wayland and report compatibility issues to application developersGNOME X11 REMOVALGNOME X11 sessions cannot be restored on Ubuntu 26.04. The X11 code was completely removed from GNOME 49 upstream, making it impossible to run GNOME Shell on X11 regardless of Xorg installation.Applications Not Starting Under X11Some applications may fail to start in X11 sessions due to Wayland-specific dependencies. Check application output for errors:$ application-name 21 | grep -i displayIf the application expects Wayland, you may need to:Check for X11-compatible versions or flagsInstall X11-specific packages (e.g.,qt5-x11extrasfor Qt applications)Set theQT_QPA_PLATFORMxcbenvironment variable for Qt applicationsPoor Performance or TearingIf you experience screen tearing or poor performance under X11:First, enable the compositor if your desktop environment has one disabled. For Xfce:$ xfconf-query -c xfwm4 -p /general/use_compositing -s trueFor environments using Compton/Picom, install and configure it:$ sudo apt install picom -yAdditionally, verify that your graphics drivers are properly installed and configured. Proprietary drivers often provide better performance than open-source alternatives for NVIDIA hardware.Package Conflict: libpeas During Desktop Environment InstallationWhen installing desktop environments like Cinnamon, MATE, or Xfce, you may encounter a package conflict error with libpeas:dpkg: error processing archive /var/cache/apt/archives/libpeas-1.0-1_1.38.1-1_amd64.deb (--unpack): trying to overwrite /usr/lib/x86_64-linux-gnu/libpeas-1.0/loaders/libpython3loader.so, which is also in package libpeas-1.0-0:amd64This error occurs when transitioning between libpeas package versions, where both the old (libpeas-1.0-0) and new (libpeas-1.0-1) versions contain the same file. The package manager cannot proceed because it would overwrite an existing file.To resolve this conflict, force dpkg to overwrite the conflicting file:$ sudo dpkg -i --force-overwrite /var/cache/apt/archives/libpeas-1.0-1_1.38.1-1_amd64.deb $ sudo apt --fix-broken installThe first command forces installation of the new package version, overwriting the conflicting file. The second command resolves any remaining dependency issues and completes the installation. After these commands complete successfully, your desktop environment installation will proceed normally.PACKAGE CONFLICTSPackage conflicts during Ubuntu 26.04’s development cycle are not uncommon as packages transition between versions. The--force-overwriteflag should only be used when you understand the conflict involves identical files from different package versions.ConclusionInstalling X11 on Ubuntu 26.04 requires understanding the display server landscape changes and taking deliberate installation steps. While Wayland represents the future of Linux graphics, X11 remains available for users who need it for compatibility, specific applications, or hardware requirements. By installing base Xorg packages and desktop-specific X11 sessions, you can maintain access to traditional X11 functionality alongside modern Wayland capabilities.Remember that X11 support is gradually diminishing across the Linux ecosystem. KDE Plasma plans to remove X11 in version 6.8, and GNOME has already completed its transition. Therefore, treat X11 as a transitional solution while working toward Wayland compatibility for your workflows. For more information about X11 and Xorg configuration, consult the official X.Org Foundation documentation.Frequently Asked QuestionsCan I install GNOME with X11 on Ubuntu 26.04?No, GNOME completely removed X11 support code in GNOME 49, which ships with Ubuntu 26.04. There is no way to restore GNOME X11 sessions on Ubuntu 26.04. Users requiring GNOME with X11 should use Ubuntu 24.04 LTS, which maintains GNOME X11 sessions until 2029, or switch to alternative desktop environments like Xfce, MATE, or Cinnamon that continue supporting X11.Will installing X11 affect my existing Wayland session?No, installing X11 does not affect or interfere with Wayland sessions. Both display servers can coexist on the same system, and you can freely switch between them at login. Your desktop environment, applications, and settings remain separate for each session type, allowing you to use whichever works best for specific tasks or applications.How do I know if I’m currently using X11 or Wayland?Run the commandecho $XDG_SESSION_TYPEin a terminal. It will return either “x11” or “wayland” indicating your current display server. You can also check by runningloginctl show-session $(loginctl | grep $(whoami) | awk {print $1}) -p Typefor more detailed session information from systemd’s login manager.Which desktop environments still support X11 in Ubuntu 26.04?Xfce, MATE, Cinnamon, and LXQt all maintain full X11 support and include it by default when installed. KDE Plasma supports X11 through an optional package (plasma-session-x11) but plans to remove support in Plasma 6.8. GNOME has completely removed X11 support and cannot run X11 sessions on Ubuntu 26.04 or later versions.Is X11 being completely removed from Ubuntu?No, the Xorg packages remain available in Ubuntu repositories. What has changed is that X11 sessions are no longer installed or configured by default for major desktop environments. Users who need X11 can still install it manually. However, upstream desktop environment projects are gradually phasing out X11 support, so long-term availability depends on those upstream decisions rather than Ubuntu itself.Related Posts:Wayland Display Server Guide on Ubuntu 26.04Ubuntu Wayland: Enable and Disable GuideHow to Disable Wayland on Ubuntu 26.04Ubuntu 26.04: Release Date and New Features in…How to Change Default Desktop Environment on Ubuntu 26.04Ultimate Web Server Benchmark: Apache, NGINX,…Categories System AdministrationHow to Install KDE Plasma on Ubuntu 26.04How to Install Xfce on Ubuntu 26.04