Graph returned an error: Invalid appsecret_proof provided in the API argument
<p>i am using facebook PHP sdk (v4) to fetch user information,
after installing SDK, i add the code</p>

<pre><code>$fb = new Facebook\Facebook([
  'app_id' =&gt; 'my app id',
  'app_secret' =&gt; 'my app secret',
  'default_graph_version' =&gt; 'v2.5',
]);

try {
  // Returns a `Facebook\FacebookResponse` object
 $access_token= //copied from my https://developers.facebook.com/tools/explorer/
  $response = $fb-&gt;get('/me?fields=id,name', '$access_token');
} catch(Facebook\Exceptions\FacebookResponseException $e) {
  echo 'Graph returned an error: ' . $e-&gt;getMessage();
  exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
  echo 'Facebook SDK returned an error: ' . $e-&gt;getMessage();
  exit;
}

$user = $response-&gt;getGraphUser();

echo 'Name: ' . $user['name'];
</code></pre>

<p>but when i run the page it gives me this error, </p>

<pre><code>Graph returned an error: Invalid appsecret_proof provided in the API argument
</code></pre>

<p>i am copying the app secret correctly, what could be the reason for such error and how should i fix this ? </p>