title: how to fix 'InvalidRegistration' FCM
body: <p>I'm getting the InvalidRegistration error in response of my post request for sending push notification.</p>
  
  <p>When I use the Firebase console to send push notification it works all fine.
  so I copy the exact registration token I've used in console. I also get my api-key from my project-settings/cloud-messaging. 
  for sending the post request I've used postman. 
  I've sent my post request to <a href="https://fcm.googleapis.com/fcm/send" rel="nofollow noreferrer">https://fcm.googleapis.com/fcm/send</a></p>
  
  <p>my postman header has this attributes:</p>
  
  <pre><code>key: Authorization value: key=&lt;api-key-i-got-from-console&gt;
  key: Content-Type value: application/json
  </code></pre>
  
  <p>my body is:</p>
  
  <pre><code>{
   "to" : "fDj8iG5ajZI:APA91bHfs_AjdxOc5Qn-1Plr_OfitrdCTchb4syhPGC0DhPMGiWggJ9mQ5W00ombqowlUSCUOfH_0N3KA-KF0VjQvj5mcMNUMUBgTblpsNzra60kwrbtH2ikfdBa8lenh__olBpGZD4O'",
   "collapse_key" : "type_a",
   "notification" : {
       "body" : "plz work",
       "title": "title"
   },
  }
  </code></pre>
  
  <p>I get this response from the Firebase</p>
  
  <pre><code>{
      "multicast_id": 5801302802423881516,
      "success": 0,
      "failure": 1,
      "canonical_ids": 0,
      "results": [
          {
              "error": "InvalidRegistration"
          }
      ]
  }
  </code></pre>
  
  <p>I did the same with fcm and django-push-notification and got the same result  I have no clue what am I doing wrong since my token works with the console and I can send push notifications from the console.</p>