I've been trying to make a slack Bolt App, but keep running into problems using socket mode. I looked into turning off socket mode and instead using a request url, but Ngrok, Vortex, and other services made to handle HTTP requests all seem to fail the challenge parameter sent by slack for verification. The error message is "Your URL didn't respond with the value of the challenge parameter". On ngrok, it just says "Error 405 Method Not Allowed". I was wondering if anyone knew why this occurred or had an alternative to ngrok that would provide me with a working Request URL. Alternatively if you also know of a way to send HTTP POST request while slack app is in socket mode, feel free to respond as well. Image of error from Slack Events page
add /slack/events
after the ngrok link, then it works (I assume the slack bolt app has default listeners only for the specific requests)