The reason property is read-only and returns a string detailing the reason for the error. Validation errors also include the URL of the Schema and the node within the Schema that corresponds to the error.

In the following example the file 'staff.xml' is loaded which includes an error: the second employee element does not include an 'ssn' attribute which is required by the DTD. If a parse error occurs, as it does in this case, an alert displays the number of the line where it occurs, and the reason why.

Note:
Where no parse error occurs, the errorCode property returns 0.

XML:
<staff>
   <employee ssn="123456" pay="3">
      <name>John Sullivan</name>
      <position>senior executive</position>
   </employee>
   <employee>
      <name>Mary Lopez</name>
      <position>personal assistant</position>
   </employee>
</staff>

Code (VBScript):
Set objXMLDoc = CreateObject("Microsoft.XMLDOM")
objXMLDoc.async = False
objXMLDoc.load("staff.xml")
Set ParseErr = objXMLDoc.parseError
If ParseErr.errorCode <> 0 Then
   alert("Error on Line: " & ParseErr.line & vbCrLf & ParseErr.reason)
End If

The alert displays the following message:

Output:
Error on Line: 10
Element content is invalid according to the DTD/Schema.
Expecting: #PCDATA