My hypothesis on why Lemmy is rejecting valid activities

<p> <p>I have not been able to successfully post to a Lemmy instance either as a post or a comment. A cryptic error message is returned where the error is unknown and the message is a generic message:</p><pre><code class="language-json">{"error":"unknown","message":"data did not match any variant of untagged enum AnnouncableActivities"}</code></pre><p>From my logs, it seems this is happening:</p><ol><li>I make a valid ActivityPub request with the audience of a community (or cc a user).</li><li>Lemmy makes an ActivityPub request back at me at <code>/</code>.</li><li>My web site does not handle ActivityPub at <code>/</code>, and responds with a <code>text/plain</code> error message. This is default behavior in Drupal.</li><li>Lemm...</li></ol></p>