What are profiles?

Thunderbird saves information such as addresses, messages, passwords and user preferences in a set of files called a profile. This profile is stored in a location separate from the Thunderbird applicationprogram files. More information about Thunderbird profiles can be found here.

What profile changes were made in Thunderbird 68?

Some users have multiple program installations of Thunderbird on the same computer; for example, Thunderbird 38, Thunderbird 45, Thunderbird 52 and Thunderbird 60, each installed in a separate applicationprogram folder. In these older Thunderbird installations it was allowed to share the same profile by default.

However, with version 68 and newer versions a dedicated profile is used for each program installation of Thunderbird (including Nightly and Beta). This makes Thunderbird more stable when switching between installations on the same computer, and also allows you to run different installations of Thunderbird at the same time.

You will not lose any personal data or customizations. Previous profile data is saved and associated with the first Thunderbird installation that was opened after this change. Details of why these changes were made is explained in the Firefox article Understanding in depth the profile per installation feature.

What are my options?

If you do nothing, your profile data will be different with each installation of Thunderbird.

Can I change which Thunderbird installation uses my previously shared profile?

Yes. You can use the Profile Manager for any installation to set a new default profile for that particular installation. Directions are available in the Profile Manager article. See also the Recover user data missing after Thunderbird update article.

What happens to my profile if I downgrade to a previous version of Thunderbird?

If you try to launch a Thunderbird installation with a profile that was last used by a newer version, you will see a warning that using an older version of Thunderbird can corrupt profile data, such as:

You have two choices:

1. Create a new profile - Click the Create New Profile button to start Thunderbird with a new profile. Creating a new profile can avoid corruption issues.
2. Use an old profile using an override - click the Exit button and proceed to use the "old", previously used profile:
   • In the directory in which Thunderbird is installed (according to Help > Troubleshooting Information), Launch Thunderbird through the command line with the --allow-downgrade parameter to override downgrade protection.

Downgrade protection started with Thunderbird version 68, to force each Thunderbird installation to use a separate profile. In this way, any previous profile data is saved and associated with the first Thunderbird installation which opened it. When you run an older Thunderbird with a new profile, a profile previously used in the higher version is still available in the Profile Manager for use by the more recent version of Thunderbird.

I already use separate profiles for my different Thunderbird installations

If you have already manually created separate profiles for different installations, you will not notice the change.