UPGRADE WARNING! PLEASE READ!

You MUST absolutely do a full backup of your profile before upgrading from a version earlier than SeaMonkey 2.53.1. This version of SeaMonkey makes changes to your profile that can't be reverted in cases where you need to go back to the older version.

The Mozilla backend code SeaMonkey is based on, now usually incorporates breaking changes in every release. This is especially true for the Mozilla Gecko add-ons code and the JavaScript interpreter. Consequently, some older extensions may no longer function properly. If you experience any problems please refer to the troubleshooting section first. Especially try to disable extensions first and check if this makes a difference.

Important only if you upgrade from 2.49.5 or an earlier version: Due to changes in the user profile, if you have set a master password, you will have to remove it before upgrading to SeaMonkey 2.53.6. After a successful upgrade, don't forget to manually remove the files key3.db and cert8.db in your profile afterwards, as they include credentials and passwords no longer protected by a master password. You can find the path to your profile folder entering the special about:support URL in a SeaMonkey browser window.

You can remove your master password by providing an empty password in the "Change Master Password" dialog. Do not use the "Reset Password" function. You will lose all stored passwords this way.

If you have a SeaMonkey 2.53.1 or 2.53.2 language pack installed you need to remove it before upgrading to this version. These language pack versions were marked to be compatible with all Seamonkey 2.53.x releases and cause breakage when used with a different version. You can then install one of the provided 2.53.6 language packs from the download section after installation of the base product.