title: Madelineproto internal peer database error when try getFullUser
body: <p>Help me please.</p>
  <p>Through the Madelineproto library, I'm trying to get information about the telegram user, but I get an error:</p>
  <blockquote>
  <p>This peer is not present in the internal peer database</p>
  </blockquote>
  <p>I tried like this and always got this error:</p>
  <pre><code>$MadelineProto-&gt;users-&gt;getFullUser(['id' =&gt; 'xxxxxx']);
  $MadelineProto-&gt;users-&gt;getFullUser(['id' =&gt; 'user#xxxxxx']);
  </code></pre>
  <p>The documentation has the answer:</p>
  <blockquote>
  <p>this error means you have tried sending a message to a peer that does
  not exist or is not present in MadelineProto’s internal peer database:
  in fact, @dd is not a valid telegram username.</p>
  </blockquote>
  <p>But I don't understand what that means, because I use my id, which is definitely working. What is an internal peer database and how to work with it to fix this error?</p>