MongoError: ns not found when try to drop collection
<p>Mongoose throw an error i.e, "<strong>MongoError: ns not found</strong>" when i try to drop collection.</p>

<p>Here is my mongoose code:</p>

<pre><code>var mongoose = require('bluebird').promisifyAll(require('mongoose'));
......
......
......   
mongoose.connection.db.dropCollection("myCollection",function(err,affect){
   console.log('err',err);

})
</code></pre>

<p>Error:</p>

<blockquote>
  <p>err { [MongoError: ns not found]<br>
  name: 'MongoError',<br>
   message: 'ns
  not found',<br>
  ok: 0,<br>
  errmsg: 'ns not found' }</p>
</blockquote>