title: Debugging save() returning false CakePHP 3.0
body: <p>I have some code which has broken somewhere along the way and I'm having trouble debugging it.</p>
  
  <p>This is a simplified version of it.</p>
  
  <pre><code>$data = $this-&gt;request-&gt;data;
  
  $form = $this-&gt;Forms-&gt;get($data['id'], [
      'contain' =&gt; ['FieldsForms' =&gt; ['data']
      ]
  ]);
  
  $form = $this-&gt;Forms-&gt;patchEntity($form, $data,
      ['associated' =&gt; [
          'FieldsForms.Data',
  
      ]
  ]);
  
  if ($this-&gt;Forms-&gt;save($form)) {
      // sunshine and rainbows
  } else {
      // wailing and gnashing of teeth
  }
  </code></pre>
  
  <p>I'm left wailing and gnashing teeth without any errors, as far as I can see if I debug the $data it looks like it's ok (though since it's fairly long and contains a bunch of UUIDs it's possible I'm missing something).</p>
  
  <p>Validation errors is empty.</p>
  
  <p>The save is returning false - any suggestions on how to debug this might save what sanity I have left.</p>
  
  <p>Thanks!</p>