Mozilla changed the application identifier (capital to lowercase) in June 2026.

Introduction

Firefox and Thunderbird applications can be installed from:

• DEB file (dpkg -i package_name)
• repository (apt) via "Application Center" or package managers synaptic and aptitude.
• Snap store
• Flatpak store

This article refers to the last two options.

0. Checking Firefox and Thunderbird installation methods

printf "\n**Checking Firefox and Thunderbird Installation...**\n\n"\
&& echo "Firefox dpkg: $(dpkg -s firefox | grep Status)" \
&& echo "Firefox apt:" && apt list --installed firefox > /dev/null >&2 \
&& echo "Firefox flatpak: $(flatpak list | grep firefox)" \
&& echo "Firefox snap: $(snap list | grep firefox)" \
&& printf "\n" \
&& echo "Thunderbird dpkg: $(dpkg -s thunderbird | grep Status)" \
&& echo "Thunderbird apt:" && apt list --installed thunderbird > /dev/null >&2 \
&& echo "Thunderbird flatpak: $(flatpak list | grep thunderbird)" \
&& echo "Thunderbird snap: $(snap list | grep thunderbird)" \
&& printf "\n" 

1. Mozilla Firefox web browser

Mozilla currently offers two options for updating the Firefox browser: Rapid Release and Extended Support Release (ESR).

• Rapid Release: Receives major updates every four weeks and minor updates such as crash fixes and security fixes as needed during those four weeks.

• Extended Support Release (ESR): Receives on average every 52 weeks, with minor updates such as crash fixes, security fixes, and policy updates as needed, but no less than every four weeks.

1.1 Installing Mozilla Firefox from the Flatpak app store

• Installing Mozilla Firefox (Rapid release channel)

Install the Flatpak application store (command for Ubuntu/Linux Mint/Debian):

sudo apt install flatpak

Installing Firefox on the operating system:

flatpak install flathub org.mozilla.firefox

Installation for this user only:

flatpak install --user flathub org.mozilla.firefox

(Firefox ESR: there is no channel in Flatpak other than an unofficial one - see link at the end of the article).

• Launching Mozilla Firefox

flatpak run org.mozilla.firefox

• Uninstalling Mozilla Firefox from Flatpak

flatpak remove org.mozilla.firefox

flatpak remove --delete-data org.mozilla.firefox

flatpak uninstall --unused

1.2 Updating Mozilla Firefox from the Flatpak app store

flatpak update org.mozilla.firefox

1.3 Installing Mozilla Firefox from the Snap App Store

Installing a stable version of Firefox:

sudo snap install firefox

"Night" version (channel "Nightly"):

sudo snap install firefox --edge

Beta version:

sudo snap install firefox --beta

1.4 Updating Mozilla Firefox from the Snap App Store

sudo snap refresh firefox

2. Thunderbird email program

In June 2026, Flatpak changed the Thunderbird app name from a capital "T" to a lowercase "t".

2.1 Installing Thunderbird from Flatpak

sudo apt install flatpak
sudo flatpak install org.mozilla.thunderbird

(Previously it was org.mozilla.Thunderbird).

2.2 Updating Thunderbird from the Flatpak App Store

• Regular version of Thunderbird

flatpak update org.mozilla.thunderbird

• ESR version of Thunderbird - with long term support

flatpak update org.mozilla.thunderbird_esr

2.3 Installing Thunderbird from Snap

• Installing ESR - Thunderbird release (instead of ESR the Release channel is recommended - see below):

sudo snap install thunderbird --channel=esr/stable

• Installing the latest stable version of Thunderbird:

sudo snap install thunderbird --channel=latest/stable

2.4 Updating Thunderbird from the Snap App Store

First, let's find out the version of Thunderbird

sudo snap info thunderbird

If "tracking: latest/stable" is displayed (that is, without "esr"), then you are already on the latest Release channel.

• Updating the ESR version - only if you want to stay on the ESR channel due to the presence of incompatible extensions:

sudo snap refresh thunderbird --channel=esr/stable

• Update to the latest stable version of Thunderbird (recommended Release channel):

sudo snap refresh thunderbird --stable

Sources:

• Channel Choices for Thunderbird Snap and Flatpak

• Installing Firefox from Flatpak

• Choose a Firefox update channel

• Unofficial Firefox ESR flatpak

• Snap: channels and tracks

• snap help refresh

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