Install on Ubuntu 11.10

From Free Pascal wiki
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This article applies to Ubuntu only.

See also: Multiplatform Programming Guide

In General


To install Lazarus you install three things:

  • fpc - the Free Pascal compiler
  • fpc-src - the source code for Free Pascal
  • Lazarus -the IDE for Free Pascal


You must install the correct version of Free Pascal for the version of Lazarus you choose. The versions below are correct.

Ubuntu 11.10 (Oneiric Ocelot)

What you want

Matching versions of Lazarus and Free Pascal are in the repository (20/02/12). They are

  • Lazarus 0.9.30-2.
  • Free Pascal 2.4.4

In Synaptic they are called Lazarus 0.9.30-2Build1, fpc, and fp.

Find and install the packages

In the Software Centre search for and install:

  • IDE for FreePascal - SDK metapackage - search under lazarus
  • Free Pascal - SDK metapackage - search under fpc
  • FreePascal - SDK source code metapackage- search under fpc

With Synaptic, install everything beginning with Laz, fpc or fp.

Problem 1

Once you have installed Lazarus, it will not work. Even if you add no code at all and compile and run everyone's favourite 'Blank form' project (having first saved it of course) you will get this error message:

Project project1 raised Exception class EInterface critical with message: ....

Solution (10 mins): Remove the Ubuntu taskbar menu and overlay scrollbars

  • Remove the taskbar

Open a terminal and try

sudo apt-get remove appmenu-gtk3 appmenu-gtk appmenu-qt

Give your password These can be re-installed if needed with the same command but put 'install' in place of 'remove'.

  • Remove the Ubuntu overlay scrollbars

Open synaptic and search for 'liboverlay-scrollbar'.

Uninstall the 2 packages highlighted. They can be re-installed if needed with Synaptic

You now need to restart Ubuntu and hope.

The 'blank form' project should now run with no errors.

Problem 2

Add a button to your 'blank form' project. In the Events tab of the Object Inspector , try to open the 'Click' event handler. You will get the error message

unit not found: Classes


unit not found: Sysutils

Solution (10 mins): Reconfigure Lazarus as sudo

This can be solved as follows:

  • Open Lazarus as sudo

Open a terminal and start Lazarus as sudo with

gksudo StartLazarus

Give your sudo password

  • Rescan the Pascal source directory

In Lazarus choose

 Tools -> Rescan FPC source directory
  • Rebuild Lazarus

In Lazarus choose

Tools -> BuildLazarus with profile:Build all
  • Close Lazarus.

You should now be able to open Lazarus normally and create a project with a button that is clickable!'

'Hello World' here we come.

Oh Joy!

Lazarus Forum

There are several threads that are useful

Forgetting to install Free Pascal source code

Solving problem 1

Solving problem 2

More about problem 2

Installing using debs


It's in German. It is very clear. In this case, after the installation, Lazarus ran without problem - mine didn't.

You tube showing install

Problem 2 image


Ubuntu 10.04 LTS (Lucid Lynx)

The version in this repository is Lazarus which is quite old. It installs via synaptic and it then works.

Install from .deb files

If you want to install a newer version using .deb files then see the wiki page

How to install from .deb files

See also