code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/IllegalStateException.html" title="class or interface in java.lang" class="external-link">IllegalStateException</a></code> - If the completion couldn't be found</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="registerAsyncCompletion(java.lang.String,co.aikar.commands.CommandCompletions.AsyncCommandCompletionHandler)">
<h3>registerAsyncCompletion</h3>
<div class="member-signature"><span class="modifiers">public</span>&nbsp;<span c