https://frikyfriky11.github.io/tags/apt/Recent content in Apt on frikyfriky11HugoenWed, 27 May 2026 20:10:00 +0200https://frikyfriky11.github.io/posts/the-bath-time-bug-when-unattended-upgrades-swaps-your-dotnet-runtime/Wed, 27 May 2026 20:10:00 +0200https://frikyfriky11.github.io/posts/the-bath-time-bug-when-unattended-upgrades-swaps-your-dotnet-runtime/<h2 id="tldr"> TL;DR <a class="heading-link" href="#tldr"> <i class="fa-solid fa-link" aria-hidden="true" title="Link to heading"></i> <span class="sr-only">Link to heading</span> </a> </h2> <p>If a long-running .NET dev server suddenly throws something like:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#282a36;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-gdscript3" data-lang="gdscript3"><span style="display:flex;"><span>System<span style="color:#ff79c6">.</span>IO<span style="color:#ff79c6">.</span>FileNotFoundException: Could <span style="color:#ff79c6">not</span> <span style="color:#8be9fd;font-style:italic">load</span> file <span style="color:#ff79c6">or</span> assembly </span></span><span style="display:flex;"><span><span style="color:#f1fa8c">&#39;System.Drawing.Primitives, Version=8.0.0.0, ...&#39;</span><span style="color:#ff79c6">.</span> The system cannot find the file specified<span style="color:#ff79c6">.</span> </span></span></code></pre></div><p>…for an assembly you can plainly see exists on disk, the most likely culprit is this:</p> <ul> <li>Ubuntu&rsquo;s <code>unattended-upgrades</code> silently upgraded your .NET runtime (e.g. <code>8.0.26</code> → <code>8.0.27</code>) <strong>while your server was running</strong>.</li> <li>The old runtime folder it was bound to got deleted out from under it.</li> <li>.NET loads many framework assemblies <strong>lazily</strong>, so everything looked fine until the <em>first</em> time a code path needed that one specific assembly — and then it went looking in a folder that no longer existed.</li> </ul> <p><strong>The fix:</strong> restart your <code>dotnet run</code>. No code change. That&rsquo;s it. The rest of this post is <em>how I figured that out</em>, because the method is more useful than the fix.</p>