title: DATA_ERR: DOM IDBDatabase Exception 5 in Chrome, how to fix?
body: <p>Code like this:</p>
  
  <pre><code>var transaction = db.transaction(["main"], IDBTransaction.READ_WRITE);
  var store = transaction.objectStore("main");
  var request = store.add(object);
  </code></pre>
  
  <p>It work correctly in Firefox, but in Chrome it throws "DATA_ERR: DOM IDBDatabase Exception 5" at the last line. What does this exception means? How to fix it?</p>