title: “Only reserved document ids may start with underscore." when trying to use _find
body: <p>I'm working with CouchDB and am trying to search a db using _find. I am currently running into the following error:</p>
  
  <pre><code>error: 'illegal_docid',
    reason: 'Only reserved document ids may start with underscore.',
    scope: 'couch',
    statusCode: 400,
    request:
     { method: 'POST',
       headers:
        { 'content-type': 'application/json',
          accept: 'application/json',
          Host: 'example.com',
          Referer: 'https://example.com' },
       uri: 'http://XXXXXX:XXXXXX@206.189.178.130:5984/gc_common/_find',
       body: '{"selector":{"_id":"taglist"}}' },
    headers:
     { date: 'Thu, 25 Jul 2019 22:04:09 GMT',
       'content-type': 'application/json',
       connection: 'close',
       'cache-control': 'must-revalidate',
       statusCode: 400,
       uri: 'http://XXXXXX:XXXXXX@206.189.178.130:5984/gc_common/_find' },
    errid: 'non_200',
    description: 'couch returned 400' }
  </code></pre>