A new entity was found through the relationship
<p>The error message:</p>

<blockquote>
  <p>A new entity was found through the relationship
  'AppBundle\Entity\Tarifa#pesos' that was not configured to cascade
  persist operations for entity:
  AppBundle\Entity\TarifaPeso@0000000072d3bd4300000000232470d3. To solve
  this issue: Either explicitly call EntityManager#persist() on this
  unknown entity or configure cascade persist this association in the
  mapping for example @ManyToOne(..,cascade={"persist"}). If you cannot
  find out which entity causes the problem implement
  'AppBundle\Entity\TarifaPeso#__toString()' to get a clue.</p>
</blockquote>

<p>Tarifa.php</p>

<pre><code>/**
 * @ORM\OneToMany(targetEntity="TarifaPeso", mappedBy="tarifa")
 */
private $pesos;
</code></pre>

<p>TarifaPeso.php</p>

<pre><code>/**
 * @ORM\ManyToOne(targetEntity="Tarifa", inversedBy="pesos", cascade={"persist"})
 * @ORM\JoinColumn(name="tarifa_id", referencedColumnName="id")
 */
private $tarifa;
</code></pre>

<p>TarifaType.php</p>

<pre><code>        -&gt;add('pesos', CollectionType::class, array(
            'entry_type'   =&gt; TarifaPesoType::class,
            'allow_add'    =&gt; true,
            'allow_delete' =&gt; true,
            'by_reference' =&gt; false
        ))
</code></pre>

<p>The controller...</p>

<pre><code>public function newAction(Request $request)
{
    $tarifa = new Tarifa();

    $form = $this-&gt;createForm('AppBundle\Form\TarifaType', $tarifa);

    $form-&gt;handleRequest($request);

    if ($form-&gt;isSubmitted() &amp;&amp; $form-&gt;isValid()) {

        $entityManager = $this-&gt;getDoctrine()-&gt;getManager();
        $entityManager-&gt;persist($tarifa);
        $entityManager-&gt;flush();

        $this-&gt;addFlash('success', 'project.created_successfully');

        return $this-&gt;redirectToRoute('admin_post_index');
    }

    return $this-&gt;render('admin/tarifas/new.html.twig', array(
        'form' =&gt; $form-&gt;createView(),
    ));
}
</code></pre>

<p>What am I missing? Really exhausted... please any help?</p>