Hello, 

first things first :)
Umbraco version: 6.2.2
Courier version: Courier_2.7.8.43.v6 

We have a 3 environment setup TEST - ACC - PROD ( load balanced & behind akamai, courier pushes to internal url of the master environment). 

This was a clean umbraco setup 6.2.1 (july 2014) with courier 2.7.8.x (can't remember version number, latest available at that moment). All of a sudden (few weeks ago) we have begin experiencing nodes that would not show there updates on the PROD (pushed with Courier). After trying a few times they would suddenly popup. A week later we were having trouble with locallinks. They would appear in TEST as locallink: ID and in ACC as locallink:GUID . I know Courier does this replace on TEST in order to map it to the same node on ACC. But it seemed that never happened.

We decided to upgrade to the newest version 2.7.8.43 (hotfix) first. 

And then we dived into the logs which uncoverd this issue: 

6-11-2014 22:55:22; Umbraco.Courier.DataResolvers.LocalLinks: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> NHibernate.NonUniqueResultException: query did not return a unique result: 12
   at NHibernate.Impl.AbstractQueryImpl.UniqueElement(IList list)
   at NHibernate.Impl.AbstractQueryImpl.UniqueResult[T]()
   at Umbraco.Courier.Persistence.V6.NHibernate.NHibernateProvider.GetNodeId(Guid uniqueId)
   at Umbraco.Courier.DataResolvers.Helpers.LocalLinkResolver.<replaceGuidWithID>b__0(Match match)
   at System.Text.RegularExpressions.RegexReplacement.Replace(MatchEvaluator evaluator, Regex regex, String input, Int32 count, Int32 startat)
   at System.Text.RegularExpressions.Regex.Replace(String input, MatchEvaluator evaluator, Int32 count, Int32 startat)
   at System.Text.RegularExpressions.Regex.Replace(String input, MatchEvaluator evaluator)
   at System.Text.RegularExpressions.Regex.Replace(String input, String pattern, MatchEvaluator evaluator, RegexOptions options)
   at Umbraco.Courier.DataResolvers.Helpers.LocalLinkResolver.replaceGuidWithID(String val)
   at Umbraco.Courier.DataResolvers.Helpers.LocalLinkResolver.ReplaceLocalLinks(String value, Boolean toUnique, Item item)
   at Umbraco.Courier.DataResolvers.LocalLinks.Extracting(Item item)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Umbraco.Courier.Core.ResolutionManager.executeResolver(Item item, ItemEvent e, ItemProvider provider)

If I understand the error correctly it searches the node with the guid, but finds 12 nodes?? 

Any advice would be greatly appreciated, 

thanks, 

Gerty