Programatically Finding Error Web Parts on a Web Part Page

So, after your Sharepoint V2 to V3 migration your site collection is full of ErrorWebParts? Here is some XPATH that you can use when iterating through your site (while calling sharepoint web services) in order to find the the ErrorWebPart identifiers:

XmlDocument doc = new XmlDocument();
doc.LoadXml(nd.OuterXml); //GetWebPartProperties2 result set

XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("wpp", "http://microsoft.com/sharepoint/webpartpages");
nsmgr.AddNamespace("wp", "http://schemas.microsoft.com/WebPart/v3");
                
XmlNode ndEmptyPartID = doc.SelectSingleNode(
 "/wpp:WebParts/wpp:WebPart[" + 
 "wp:webPart/wp:metaData/wp:type/@name='" + 
 "Microsoft.SharePoint.WebPartPages.ErrorWebPart, Microsoft.SharePoint, Version=12.0.0.0," +
 "Culture=neutral, PublicKeyToken=71e9bce111e9429c" +
 "']/@ID",
 nsmgr);
Guid WebPartID;
if (ndEmptyPartID != null)
{
  WebPartID = new Guid(ndEmptyPartID.Value);
}