tmux versions and changelog: the latest release is 3.8

What is the latest version of tmux?

$ tmux -V
tmux 3.8

The official sources are the CHANGES file (the full changelog, maintained by the tmux authors) and the GitHub releases page, which has the source tarball for each version. Version numbers are simple: 3.8 is a feature release and a letter (3.7a, 3.7b, 3.7c) marks a bug-fix release of the same series. There is no 4.0 announced; after 3.9 comes whatever the developers decide.

How to check your tmux version (client and server)

There are two versions to know, and after an upgrade they can differ:

tmux --version does not work (tmux only accepts -V), and builds from Git report next-3.9. The server is started once and keeps running until it is killed, so after a package upgrade the new client can be talking to an old server. That is exactly what this real screenshot shows: Ubuntu's tmux 3.4 server still running, with a freshly installed 3.8 client in the PATH.

Real screenshot · tmux 3.4

The status line color is a giveaway: plain green is the pre-3.8 default, yellow-green is 3.8's new theme. If the two versions differ, restart the server as described in How to upgrade tmux.

What changes when you upgrade to 3.8?

Pick the version you have now. The list shows what you gain, and which defaults change under you, when you move to 3.8. Ubuntu 24.04 users are on 3.4, Ubuntu 22.04 and RHEL 9 users on 3.2a.

Summarized from the official CHANGES file; defaults checked on real tmux 3.4 and 3.8 builds with no config file.

What's new in tmux 3.8

tmux 3.8 (8 October 2026) is one of the largest releases in years. The headline is that floating panes, introduced in 3.7, are now complete, plus built-in themes and an event system for hooks.

• Floating panes, finished. Move and resize them from the keyboard (Ctrl+b g table) or mouse, tile and float with Ctrl+b @, swap-pane, break-pane and join-pane work with them, Ctrl+drag creates one, and new-pane -O makes a modal pane that blocks the others. Floating panes guide.
• Themes. A theme option (detect, terminal, light, dark) and color names such as themegreen in styles. Theme config.
• Switcher. switch-mode, bound to Ctrl+b Tab (windows) and Ctrl+b Shift+Tab (sessions).
• Hooks as events. set-hook -B monitors a format every second, wait-for -E waits for events, and new hooks cover pane activity, moves, resizes and OSC 133 shell prompts. Scripting guide.
• Customize mode (Ctrl+b C) shows hooks and environment, opens values in an editor with e, and filters to changed items with C.
• Smaller additions: auto-hiding scrollbars, clear-on-attach, live-refreshing copy mode (refresh-on, r to refresh once), capture-pane -I, new-window -E for an empty pane, remain-on-exit failed-key, kill-session -a -f filters, Ctrl+b T for pane titles, and left/right margin support for WezTerm and Ghostty.

What's new in tmux 3.7 (June 2026)

3.7 was tagged on 26 June 2026, followed by bug-fix releases 3.7a and 3.7b (1 July) and 3.7c (17 August; on macOS it builds with jemalloc to avoid a calloc bug).

• Floating panes: panes that sit above the layout like popups but behave like normal panes. Create one with new-pane, bound to Ctrl+b *. In 3.7 they could only be moved and resized with the mouse.
• Copy mode line numbers with copy-mode-line-numbers (absolute, relative, hybrid). Copy mode guide.
• message-format controls how messages and prompts are drawn; they can now cover only part of the status line.
• Synchronized output (DECSET 2026) so fast-updating programs such as AI agents and TUIs do not tear.
• focus-follows-mouse, get-clipboard, remain-on-exit key, kill-session -g for session groups, run-shell arguments as #{1}, and sorting with -O for list-keys and the list commands.

What's new in tmux 3.6 (November 2025)

3.6 was tagged on 26 November 2025; 3.6a (5 December 2025) fixed a crash and several regressions, and 3.6b (20 May 2026) fixed image handling. Ubuntu 26.04 LTS ships 3.6a.

• Pane scrollbars: set -g pane-scrollbars on (or modal for copy mode only), with position and style options.
• Theme reporting: tmux tells programs whether the terminal is light or dark (mode 2031), guessing from the background when the terminal cannot say.
• Nicer default second and third status lines, tiled-layout-max-columns, case-insensitive search in modes, codepoint-widths and variation-selector-always-wide for emoji, default-client-command, the no-detach-on-destroy client option, and OSC 52 detection from the terminal's device attributes.

What's new in tmux 3.5 (September 2024)

3.5 was tagged on 27 September 2024, and 3.5a on 5 October 2024 (Debian 13 ships 3.5a).

• escape-time defaults to 10 ms instead of 500 ms. This removes the delay after Esc that Vim users used to fix by hand.
• Extended keys revamp to match xterm more closely, with extended-keys-format.
• Mirrored main-horizontal and main-vertical layouts, prefix-timeout, allow-set-title, the command-error hook, copy-mode -d and hyperlinks shown in copy mode.
• 3.5a reverted one 3.5 change: #(), run-shell and if-shell use /bin/sh again; default-shell applies only to popups.

For 3.4 and earlier, see the version history below and the CHANGES file.

Which tmux version does your OS ship?

Most people run whatever their package manager installed. On 28 October 2026:

Full per-distribution tables are on the Linux install page, with the macOS and Windows equivalents.

How to upgrade tmux

Upgrading is two steps: install the new version with the same tool you used before, then restart the tmux server. Pick your system:

$ brew update && brew upgrade tmux
$ tmux kill-server

$ sudo apt update && sudo apt install --only-upgrade tmux
$ tmux kill-server

$ sudo apt update && sudo apt upgrade
$ tmux kill-server

Why you must restart the server after upgrading

tmux is a client and a server. The server is the long-running process that owns your sessions; it was started from the old binary and keeps running that code after the package manager replaces the file on disk. When the client and server versions use different protocols, the new client cannot talk to the old server at all. This real capture shows the opposite case, an old 3.4 client meeting a running 3.8 server:

Real screenshot · tmux 3.8

"server exited unexpectedly" is misleading here: we checked, and the 3.8 server was still running with its session intact. The client just could not speak its protocol. Other combinations print protocol version mismatch (client N, server M), or they work but you are silently still on old defaults (as in the screenshot above).

$ tmux kill-server
$ tmux new -s main
$ tmux display -p '#{version}'
3.8

kill-server ends every session and the programs in them, so save your work first. To keep long jobs alive, start the new version on a separate socket and move over when they finish: tmux -L new runs a second, independent server. To bring back windows and layouts after a restart, use tmux-resurrect. Before upgrading across several versions, run through what changes above.

tmux version history

tmux was started by Nicholas Marriott in 2007; the first tagged release, 0.8, is from April 2009. 2026 has been the busiest year since then: six releases (3.6b to 3.8) and more commits than any year except 2009.

Dates are the git tag dates in github.com/tmux/tmux; highlights are summarized from CHANGES. This table is generated from src/data/releases.json.

tmux version FAQ