512 bytes of padding to suppress Internet Explorers Friendly error messages From: HOW TO: Turn Off the Internet Explorer 5.x and 6.x Show Friendly HTTP Error Messages Feature on the Server Side http://support.microsoft.com/kb/294807 Several frequently-seen status codes have friendly error messages that Internet Explorer 5.x displays and that effectively mask the actual text message that the server sends. However, these friendly error messages are only displayed if the response that is sent to the client is less than or equal to a specified threshold. For example, to see the exact text of an HTTP 500 response, the content length must be greater than 512 bytes.