title: Mongodump and mongorestore; field not found
body: <p>I'm trying to dump a database from another server (this works fine), then restore it on a new server (this does not work fine).</p>
  
  <p>I first run:</p>
  
  <pre><code>mongodump --host -d
  </code></pre>
  
  <p>This creates a folder <code>dump/db</code> which contains all of the bson documents.</p>
  
  <p>Then in the dump folder, I'm running:</p>
  
  <pre><code>mongorestore -d dbname db
  </code></pre>
  
  <p>This works and iterates through the files, but I get this error on <code>dbname.system.users</code></p>
  
  <pre><code>Wed May 23 02:08:05 { key: { _id: 1 }, ns: "dbname.system.users", name: "_id_" }
  Error creating index dbname.system.usersassertion: 13111 field not found, expected type 16
  </code></pre>
  
  <p>Any ideas how to resolve this?</p>