title: Flutter pub get failed many times
body: <p>I tried &quot;flutter pub get&quot; and this was the message :</p>
  <pre><code>Because flash_chat depends on flutter any from sdk which doesn't exist (unknown SDK &quot;flutterx&quot;), version solving failed.
  pub get failed (server unavailable) -- attempting retry 2 in 2 seconds...
  </code></pre>
  <p>note: flutter doctor works has no problems</p>