<h2 id="heading-issue">Issue</h2>
<p>After version upgrade, tmux failed with error:</p>
<pre><code>$ tmux
protocol version mismatch (client <span class="hljs-number">8</span>, server <span class="hljs-number">7</span>)
</code></pre><h2 id="heading-caused">Caused</h2>
<p>There is a old tmux session which still running.</p>
<h2 id="heading-resolution">Resolution</h2>
<p>Killall active tmux session</p>
<pre><code>$ sudo killall <span class="hljs-number">-9</span> tmux
</code></pre><h2 id="heading-ref">Ref:</h2>
<ul>
<li><a href="https://repost.aws/questions/QUYI1AjzuuQX6w4LYfBV6e_w/resolve-protocol-version-mismatch-error-when-launching-new-terminal-on-ssh-based-environment" class="autolinkedURL autolinkedURL-url" target="_blank">repost.aws/questions/QUYI1AjzuuQX6w4LYfBV6e..</a></li>
</ul>


## Issue
After version upgrade, tmux failed with error:
```
$ tmux
protocol version mismatch (client 8, server 7)
```

## Caused
There is a old tmux session which still running.

## Resolution
Killall active tmux session
```
$ sudo killall -9 tmux
```

## Ref:
- https://repost.aws/questions/QUYI1AjzuuQX6w4LYfBV6e_w/resolve-protocol-version-mismatch-error-when-launching-new-terminal-on-ssh-based-environment

Tmux: protocol version mismatch (client 8, server 7)

Issue

Caused

Resolution

Ref: