Where to find FCM Firebase registration ID's (in PHP, for Ionic framework)?
<p>We have build an app with the Ionic framework (we're beginners to Ionic etc), and we register the device to our Firebase account so that we can sent push messages.</p>

<p>I've now found a PHP snippet which connects to fcm via cURL. I can set a message and title, perfect.<br>
My problem is that I can't get it to work, it requires something called "registration id's". Everything I find about this makes it seem like this is super easy to find, but I can't.</p>

<p><b>Where to I find these registration ID's?</b> All I want is to send <em>all</em> registered users a notification.  </p>

<ul>
<li>I have tried about every code I could find, none work. The most obvious IMO is in the Firebase dashboard->authorisation where I find a list with User Id's (which occur after I've registered my device via the app).</li>
<li>However, this results in <code>{"error":"InvalidRegistration"}</code>. When I remove the 'to' all together, the result it "to" (not as JSON, those two characters only).</li>
<li>When I send messages from the Firebase console get send almost instantly</li>
<li>I've done <code>user.getToken()</code> which results in quite a long string. This doesn't work either</li>
<li>I've got a token provided by <a href="https://github.com/fechanique/cordova-plugin-fcm" rel="nofollow noreferrer">the FCMPlugin</a>, but thats still not the right registration id</li>
</ul>

<p><a href="https://gist.github.com/prime31/5675017" rel="nofollow noreferrer">The code I am using can be found here.</a> I've changed 'registration_ids'-> 'to' and the 'android.googleapis.com' to 'fcm.googleapis.com' , I've read somewhere that is the new version. Other that that, the code is identical.</p>