<p dir="auto">I've followed the custom-express-example to set custom server routes. Next/Link is working properly in client-side, but when the page is refreshed, the error message with 'not found' appears in console, regarding the files (css/images) from '/static' folder.</p>

<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/zeit/next.js/issues?q=is%3Aissue">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>
<p dir="auto">The files in static folder should be found when matches the custom routes on server.</p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto">client:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content=" &lt;Link as={`/lead/${id}`} href={`/lead?id=${id}`}&gt;"><pre class="notranslate"><code class="notranslate"> &lt;Link as={`/lead/${id}`} href={`/lead?id=${id}`}&gt;
</code></pre></div>
<p dir="auto">server:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="server.get('/lead/:id', async (req, res) =&gt; {
  return app.render(req, res, '/lead', { id: req.params.id });
});"><pre class="notranslate"><code class="notranslate">server.get('/lead/:id', async (req, res) =&gt; {
  return app.render(req, res, '/lead', { id: req.params.id });
});
</code></pre></div>
<p dir="auto">error when page is refreshed:<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/10598662/37627192-10b917ca-2bb2-11e8-916f-c18900358873.png"><img src="https://user-images.githubusercontent.com/10598662/37627192-10b917ca-2bb2-11e8-916f-c18900358873.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/10598662/37627115-b3c79992-2bb1-11e8-83ec-7411072e8032.png"><img src="https://user-images.githubusercontent.com/10598662/37627115-b3c79992-2bb1-11e8-83ec-7411072e8032.png" alt="image" style="max-width: 100%;"></a></p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>
<ol dir="auto">
<li>Define a custom route with express</li>
</ol>
<h2 dir="auto">Context</h2>
<p dir="auto">I'm trying to set routes on an Express server and pass parameters by URL. Style and image files in the static folder are not found when accessed directly by the URL or refreshing the page.</p>
<h2 dir="auto">Your Environment</h2>
<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>next</td>
<td>5.0.1-canary.15</td>
</tr>
<tr>
<td>node</td>
<td>v9.5.0</td>
</tr>
<tr>
<td>OS</td>
<td>elementary OS 0.4.1 Loki</td>
</tr>
<tr>
<td>inferno</td>
<td>^4.0.8</td>
</tr>
<tr>
<td>inferno-compat</td>
<td>^4.0.8</td>
</tr>
<tr>
<td>inferno-server</td>
<td>^4.0.8</td>
</tr>
<tr>
<td>react</td>
<td>^16.2.0</td>
</tr>
<tr>
<td>react-dom</td>
<td>^16.2.0</td>
</tr>
</tbody>
</table>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/zeit/next.js/issues?q=is%3Aissue">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<p dir="auto">I'm struggling to put Next.js and Serverless together. I could use some help with my latest issue. I don't really know if the bug is on Next.js side, or serverless side (none, I guess, it's just hard to put them together) so any help would be greatly appreciated.</p>
<p dir="auto">One of the errors I'm running into is <code class="notranslate">Error: INVALID_BUILD_ID</code>, which is on Next.js side, and I don't really know why.</p>
<p dir="auto">Explained in depth there:<br>
<a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="300072798" data-permission-text="Title is private" data-url="https://github.com/serverless/serverless/issues/4772" data-hovercard-type="issue" data-hovercard-url="/serverless/serverless/issues/4772/hovercard?comment_id=369385253&amp;comment_type=issue_comment" href="https://github.com/serverless/serverless/issues/4772#issuecomment-369385253">serverless/serverless#4772 (comment)</a></p>
<p dir="auto">Thanks!</p>