Quota errors

A quota error, which is identified by a <domain> tag value of yt:quota, identifies a problem related to irregular API usage.

For quota errors, the <code> tag will contain one of the following values:

1. too_many_recent_calls - This code indicates that the API servers have received too many calls from the same caller in a short amount of time. This error will not specify a location. The API response will not include a <location> tag for this type of error.
<?xml version='1.0' encoding='UTF-8'?>
<errors>
  <error>
    <domain>yt:quota</domain>
    <code>too_many_recent_calls</code>
  </error>
</errors>

 If you receive this error, then your application has exceeded our current limits on API calls. We recommend that you wait a few minutes and then try your request again.

2. too_many_entries - This code indicates that the user is attempting to exceed a storage limit on his account and must delete existing entries before inserting new entries. For this type of error, the <location> tag identifies the feed that caused the error.
<?xml version='1.0' encoding='UTF-8'?>
<errors>
  <error>
    <domain>yt:quota</domain>
    <code>too_many_entries</code>
    <location type='other'>https://gdata.youtube.com/feeds/users/username/uploads</location>
  </error>
</errors>

from: code.google.com