title: Why slack slash command returns "http_client_error"
body: <p>I'm trying to build a very simple Slackbot using the <a href="https://github.com/SlackAPI/bolt" rel="noreferrer">Bolt Framework</a>. I'm using ngrok to run this locally and when I invoke a slash command, ngrok just shows:</p>
  
  <p><a href="https://i.stack.imgur.com/gFLa6.png" rel="noreferrer"><img src="https://i.stack.imgur.com/gFLa6.png" alt="screengrab of ngrok"></a>
  <a href="https://i.stack.imgur.com/WUdB9.png" rel="noreferrer"><img src="https://i.stack.imgur.com/WUdB9.png" alt="screenshot of slack"></a></p>
  
  <p>According to the Bot documentation, the app uses <code>app.command()</code> to handle slash commands. This is part of my code:</p>
  
  <pre><code>const {App, LogLevel} = require("@slack/bolt");
  
  const app = new App({
    token: "XXXX",
    signingSecret: "XXXX",
    logLevel: LogLevel.DEBUG
  });
  
  // The echo command simply echoes on command
  app.command("/standup", async ({command, ack, say}) =&gt; {
    // Acknowledge command request
  
    ack();
    say(`${command.text}`);
    console.log("Entered into the app.command for /standUp");
  });
  </code></pre>
  
  <p>Within Slack, the slash command is configured like this: </p>
  
  <p><a href="https://i.stack.imgur.com/JsF7L.png" rel="noreferrer"><img src="https://i.stack.imgur.com/JsF7L.png" alt="slack_setup"></a></p>
  
  <p>The bot works when interacting with messages, but just does receive and respond to Slash commands. I'm really new to this so any info would be great or just a push in the right direction. </p>