Although Ubuntu 12.04 Precise Pangolin is LTS release, long term supported and stable GNU/Linux version, it has some issues.

We provide the list with the most common Ubuntu 12.04 Precise Pangolin problems and their solutions.

This article is regularly updated, so stay tuned!

Ubuntu 12.04 can't restart

Issue

Ubuntu 12.04 can't restart following the standard reboot procedure: 

Click system button in upper right corner > Shut down... > Restart button

It ends up in a black screen.

Solution

The reason for the problem could be a BIOS issue or the hardware setup of the system

1) Enter the command in the terminal

sudo gedit /etc/default/grub

2) Find GRUB_CMDLINE_LINUX="" and change it to GRUB_CMDLINE_LINUX=”reboot=efi”

3) Save the file and run the command:

sudo update-grub

If this is not working, try with some other parameter instead of efi (i.e.: reboot=efi). For detailed list of available parameters read this article.

There is no "Show Desktop" option

Issue

By default, Ubuntu 12.04 doesn't have enabled options to show desktop except using shortcut keys Ctrl+Super+D (the Super button is the Windows button in the most cases)

Solution

Show Desktop in Ubuntu 12.04 via CompizConfig Settings Manager (the first way)

1) Install and run CompizConfig Settings Manager

2) Click on Desktop category on left sidebar > Click on Ubuntu Unity Plugin > Select the Experimental tab

3) Mark option Show "Desktop Icon" in the launcher

The desktop icon will appear in the Unity launcher and you can click on it in order to show desktop.

For more ways to show desktop in Ubuntu 12.04 read this article.

Unity launcher auto hide problem

Issue

Many users compain that after enabling Unity Launcher auto hide, it doesn't show when cursor is moved to the left edge of the screen in Ubuntu 12.04.

Solution

The trick here is not how hard the mouse cursor is moved to the left screen edge but how far (or fast). Here are the steps that could help you in using the launcher in the way you like:

1) Install CompizConfig Settings Manager (known by its shortname CCSM)

2) After the installation, start CompizConfig Settings Manager

3) Go to Desktop > Ubuntu Unity Plugin > Experimental tab

4) Find the option "Launcher Reveal Pressure"

5) Default value is 20, but you can change it to any lower

Hibernate option missing

Issue

Ubuntu 12.04 doesn't have enabled hibernate feature by default, but you can enable it if your hardware supports hibernation.

Solution

1) Create file

/etc/polkit-1/localauthority/50-local.d/com.ubuntu.desktop.pkla

2) Add the content:

[Re-enable hibernate by default]

Identity=unix-user:*

Action=org.freedesktop.upower.hibernate

ResultActive=yes

3) Save the file, restart the machine and new menu item should appear under the system button in upper right corner

"Ubuntu 12.04 has experienced an internal error" message

Issue

Ubuntu 12.04 contains error reporting system named Apport that can send error information to Ubuntu center in case that something goes wrong on your system. There could be many reported issues caused with various reasons displaying the message error:

"Sorry, Ubuntu 12.04 has experienced an internal error"

Solution

The only solution to stop displaying error messages is to disable the Apport, the error reporting system:

1) Run the command

sudo gedit /etc/default/apport

2) Change the value of the "enabled" parameter from "1" to "0" and save the changes

Unity Launcher Hiding Behind Other Windows

Issue

In some cases, Unity Launcher goes in the background, behind all windows and the Unity Shell, and it's not possible to move it to the frontend, in front all other windows (what is its default and normal behavior). This happens no matter whether you enabled Unity Launcher auto hide option or not. Usualy, GIMP causes this annoying Unity Launcher's behavior.

Solution

Sometime, after some further use and without any additional actions, the computer could freeze for a brief moment and Unity Launcher and Dash could continue to work properly. If this doesn't happen here is the way to restart unity launcher without destroying the session and avoiding computer restarting:

1) Start terminal and run the following command:

sudo unity&disown

Screen will flick a few times and after that everything will be back again.

Can't change Ubuntu 12.04 default font

Issue

There is no configuration option for changing default font type and size in Ubuntu 12.04

Solution

1) Instal gnome tweak tool:

sudo apt-get install gnome-tweak-tool

2) Start gnome tweak tool either by click on Dash Home and entering "advanced settings" or typing command "gnome-tweak-tool" in the terminal

3) GNOME Tweak Tool window will appear

4) Select the Fonts section on the left

5) Choose your preferent default font, document, monospace and window title font as well as font size and hinting and antialiasing types.

Wireless connection doesn't remember password

Issue

Wireless connecton continue asking for password in window "Wireless Connection Authentication Required" every time the computer is started.  

Solution

1) Click on the connection icon on the taskbar

2) Select the last menu item "Edit Connections..." > Click on the Wireless tab

3) Select you connection and click the Edit button

4) Check "Connect automatically" checkbox on new window and click "Wireless Security" tab

5) Select the connection's Security (usually it is "WEP 40/128-bit Key (Hex or ASCII)")

6) Enter your password in the Key field (you can check the "Show key" checkbox if you want to see what password you entered) and click "Save..." button

GEdit is too slow

Issue

GEdit text editor is very slow in Ubuntu 12.04 Precise Pangolin

Solution

The solution is to disable File Browser plugin in GEdit.

Start GEdit and select Edit > Preferences > Choose Plugins tab > Deselect File Browser Panel plugin

Ubuntu 12.04 with low RAM is very slow

Issue

Ubuntu 12.04 Precise Pangolin could become sluggish and slow on a machine with low memory. In this case Ubuntu accesses the hard disk often and it will impact the performance very much.

Solution

Change swappines value. The lower the value is, the longer it takes before Ubuntu starts using the swap partition instead phisical memory. More about Linux swappiness read HERE.

1) Run terminal

2) Enter the command to check out current swappines value

cat /proc/sys/vm/swappiness

3) The result will probably be 60 (default value in Ubuntu for swappiness)

4) Open file /etc/sysctl.conf in a text editor, e.g.

gedit /etc/sysctl.conf

5) Go to the end of the file and enter the following parameter

# Decrease swappiness value
vm.swappiness=10

6) Save the file and restart the computer

"Hot Corner" show desktop doesn't work after restart

Issue

Our article describes how to show desktop in Ubuntu 12.04 by enabling "hot corner" feature, but in some cases the feature will not take effect after a computer is restarted.

Solution

It seems that unityshell plugin is rewritting the expo plugin configuration. Configure the expo plugin to be loaded after unityshell:

1) Start gconf-editor and find /apps/compiz-1/general/screen0/options/active_plugins key

2) Double-click on the key active_plugins will display edit window

3) Place expo under unityshell and click OK to save the changes

Ctrl+Alt+Backspace doesn't work

Issue

Ctrl+Alt+Backspace doesn't restart/kill X server and session.

Solution

This feature needs to be enabled:

System Settings... > Keyboard Layout > Options... > Key Sequence to kill X Server > Select option Ctrl+Alt+Backspace

Touchpad stop working

Issue

Touchpad can randomly stop working sometimes on laptops/netbooks/notebooks.

Solution

Disable touchpad and re-enable it again using shortcut Fn + F7.