SeaMonkey 2.0 Alpha 1

These release notes describe system requirements, installation instructions, and known issues for SeaMonkey 2.0 Alpha 1. These notes are updated when we receive feedback, so please check back for new information.

Warning! The SeaMonkey version described on this page is an outdated testing-only preview of an already released version of our Internet suite. Please download the stable release instead of this version.

What's New in SeaMonkey 2.0 Alpha 1

SeaMonkey 2.0 Alpha 1 contains the following major changes:

  • SeaMonkey switched to Toolkit, the same backend Firefox uses internally. Due to this change SeaMonkey is now much closer to Firefox as far as user profiles, add-ons and functionality of user interface elements are concerned.
  • The default location of user profiles has changed. Legacy profiles, e.g. from SeaMonkey 1.x, are migrated automatically, excluding third-party add-ons (extensions and themes). The old profile will not be touched (instead, copies are made).
  • The new Add-on Manager allows to install, update, disable and remove extensions (add-ons), themes and plugins using the same mechanisms Firefox uses. This should ease extension management and development considerably.
  • Gecko, the rendering engine used in SeaMonkey, has seen many improvements since the version used in the last stable release. Changes range from a better graphics backend (Cairo/Thebes) to improved support for fonts, CSS, DOM and JavaScript. SeaMonkey 2.0 Alpha 1 passes the Acid2 test and most of Acid3.
  • Most of the icons in the default theme have been exchanged for newer images that fit better with the look of modern desktop environments.
  • Support for Windows 95, 98, Me and NT 4 was dropped. GTK 2.10 is now required on Linux/UNIX. Support for Mac OS X 10.3 ("Panther") was also dropped.

The changes page lists more details about new features and fixes.


The SeaMonkey project provides official versions of SeaMonkey 2.0 Alpha 1 for Windows, Linux, and Mac OS X in US English and experimental language packs for a small variety of other languages. Community volunteers are also contributing builds for other platforms. You can download SeaMonkey 2.0 Alpha 1 here.

System Requirements, Installation and Uninstallation

Before installing, make sure your computer meets the system requirements. SeaMonkey 2.0 Alpha 1 will offer to migrate your data from SeaMonkey 1.x or Mozilla 1.x at the first start after installation. You can find more details about installation, profile data and uninstallation in our install and uninstall document.

Extensions and Themes

Extensions installed under SeaMonkey 1.x are not migrated to SeaMonkey 2, and may not be compatible for reinstalling in this version due to major changes in our architecture. Please report any issues to the maintainer of the extension. Extensions and Themes for SeaMonkey 2.0 Alpha 1 can be installed from the SeaMonkey Add-Ons website or the "Get Add-Ons" section in the Add-Ons manager.

Known Issues

This list covers some of the known problems with SeaMonkey 2.0 Alpha 1. Please read this before reporting any new bugs.
  • Profile Roaming is currently not working (Bug 378647)
  • MailNews account password prompts are no longer serial at startup (Bug 338549)
  • Download Manager doesn't support localization and has other slight issues - will be fixed by switching it to the Toolkit backend (Bug 381157)
  • Password Manager doesn't support localization - will be fixed by switching it to the Toolkit backend (Bug 390025)


  • Poorly designed or incompatible extensions can cause problems with SeaMonkey, including make it crash, slow down page display, etc. If you encounter strange problems relating to parts of SeaMonkey no longer working, the browser not starting, windows with strange or distorted appearance, degraded performance, etc, you may be suffering from Extension or Theme trouble. Restart SeaMonkey in Safe Mode. On Windows, start using the "Safe Mode" shortcut created in your Start menu or by running seamonkey.exe -safe-mode. On Linux, start with ./seamonkey -safe-mode and on Mac OS X, run:

    cd /Applications/
    ./seamonkey-bin -safe-mode

    When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.
  • If you uninstall an extension that is installed with your user profile (i.e. you installed it from a Web page) and then wish to install it for all user profiles using the -install-global-extension command line flag, you must restart SeaMonkey once to cleanse the profile extensions datasource of traces of that extension before installing with the switch. If you do not do this you may end up with a jammed entry in the Extensions list and will be unable to install the extension globally.
  • If you encounter strange problems relating to bookmarks, downloads, window placement, toolbars, history, or other settings, it is recommended that you try creating a new profile and attempting to reproduce the problem before filing bugs. Create a new profile by running SeaMonkey with the -P command line argument, choose the "Manage Profiles" button and then choose "Create Profile...". Migrate your settings files (Bookmarks, Saved Passwords, etc) over one by one, checking each time to see if the problems resurface. If you do find a particular profile data file is causing a problem, file a bug and attach the file.

Frequently Asked Questions

What can I do to help?
We need help from developers and the testing community to provide as much feedback as possible to make SeaMonkey even better. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla. You can also give us your feedback through this feedback form.
Why haven't you responded to the mail I sent you?
Use the newsgroup. The SeaMonkey team reads it regularly, and your email may have gotten lost.
Where can I get extensions and themes (add-ons)?
Extensions and Themes can be downloaded from SeaMonkey Add-ons.
Who makes SeaMonkey?
Lots of people. See Help->About SeaMonkey, contributors for a list of some of the people who have contributed to Mozilla and SeaMonkey.
Where's the SeaMonkey 2.0 Alpha 1 source code?
A tarball of the SeaMonkey 2.0 Alpha 1 source code is available at the download page. The latest development code can be obtained from the source repository. SeaMonkey-specific source is in the "suite" directory. Please follow the build instructions.

Other Resources and Links

The following resources contain useful information about SeaMonkey 2.0 Alpha 1: