<p dir="auto">When adding a violation error on an unmapped field, the ViolationMapper creates a PropertyPath with an empty string, which is invalid and throws an exception.<br>
Code to reproduce the issue:</p>
<div class="highlight highlight-text-html-php notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;?php
use Symfony\Bundle\SecurityBundle\Validator\Constraint\UserPassword;

        $builder-&gt;add('current_password', 'password', array(
            'mapped' =&gt; false,
            'constraints' =&gt; new UserPassword(),
        ));"><pre class="notranslate"><span class="pl-ent">&lt;?php</span>
<span class="pl-k">use</span> <span class="pl-v">Symfony</span>\<span class="pl-v">Bundle</span>\<span class="pl-v">SecurityBundle</span>\<span class="pl-v">Validator</span>\<span class="pl-v">Constraint</span>\<span class="pl-v">UserPassword</span>;

        <span class="pl-s1"><span class="pl-c1">$</span>builder</span>-&gt;<span class="pl-en">add</span>(<span class="pl-s">'current_password'</span>, <span class="pl-s">'password'</span>, <span class="pl-en">array</span>(
            <span class="pl-s">'mapped'</span> =&gt; <span class="pl-c1">false</span>,
            <span class="pl-s">'constraints'</span> =&gt; <span class="pl-k">new</span> <span class="pl-v">UserPassword</span>(),
        ));</pre></div>
<p dir="auto"><a href="https://github.com/rails/turbolinks/">https://github.com/rails/turbolinks/</a></p>
<p dir="auto">havent looked at the implementation, but imho it should GET the same content as a normal GET request to better leverage ESI and reverse proxies in general.</p>