I have noticed that when I am developing locally NHibernate works without an error, but when I deploy the ASP.NET application to other environments I will get the error: Namespace prefix 'hbm' is not defined.

It changes from various mapping files here is the stack trace:

[XPathException: Namespace prefix 'hbm' is not defined.]
MS.Internal.Xml.XPath.UndefinedXsltContext.LookupNamespace(String prefix) +1508507
MS.Internal.Xml.XPath.BaseAxisQuery.SetXsltContext(XsltContext context) +15
MS.Internal.Xml.XPath.CompiledXpathExpr.SetContext(XmlNamespaceManager nsManager) +58
System.Xml.XmlNode.SelectNodes(String xpath, XmlNamespaceManager nsmgr) +47
NHibernate.Cfg.HbmBinder.GetMetas(XmlNode node) +73
NHibernate.Cfg.HbmBinder.BindProperty(XmlNode node, Property property, Mappings mappings) +836
NHibernate.Cfg.HbmBinder.CreateProperty(IValue value, String propertyName, Type parentClass, XmlNode subnode, Mappings mappings) +323
NHibernate.Cfg.HbmBinder.PropertiesFromXML(XmlNode node, PersistentClass model, Mappings mappings) +1211
NHibernate.Cfg.HbmBinder.BindRootClass(XmlNode node, RootClass model, Mappings mappings) +2404
NHibernate.Cfg.HbmBinder.BindRoot(XmlDocument doc, Mappings mappings) +392
NHibernate.Cfg.Configuration.AddValidatedDocument(XmlDocument doc, String name) +55

Has anyone received this error before?

Thanks,
Andy

It turned out I didn't have my singleton configured correctly which was causing it to rebuild each data call.

Andy

Andy, can you explain little more what you meant "I didn't have my singleton configured correctly" we have the same problem. When we run website locally we not have problem but when make deploy to production server we received this error.

Hello,
We are currently experiencing the same error (Namespace hbm is not defined) in several websites. Does anyone know the cause of this problem?
Andy, I will also appreciate it if you explain what you meant by "i didn' t have my singleton configured correctly" and how you implement it to solve this problem.
Thanks,
Mayi