Hello, I'm stuck on this error while upgrading to Umbraco 7.4.1 from 7.1.4. It happens during the installer. According to my web config, it did complete the update to 7.4.1.

Server Error in '/' Application.

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.library.GetXmlNodeByXPath(String xpathQuery) +14

[TargetInvocationException: Exception has been thrown by the target of an invocation.]
   System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor) +0
   System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments) +92
   System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) +155
   UmbracoExamine.LegacyLibrary.GetXmlNodeByXPath(String xpathQuery) +78
   UmbracoExamine.DataServices.UmbracoContentService.GetPublishedContentByXPath(String xpath) +10
   UmbracoExamine.BaseUmbracoIndexer.GetXDocument(String xPath, String type) +89
   UmbracoExamine.BaseUmbracoIndexer.AddNodesToIndex(String xPath, String type) +20
   UmbracoExamine.BaseUmbracoIndexer.PerformIndexAll(String type) +755
   UmbracoExamine.UmbracoContentIndexer.PerformIndexAll(String type) +117
   Examine.LuceneEngine.Providers.LuceneIndexer.IndexAll(String type) in x:\Projects\Examine\Examine\Projects\Examine\LuceneEngine\Providers\LuceneIndexer.cs:829
   UmbracoExamine.BaseUmbracoIndexer.IndexAll(String type) +29
   UmbracoExamine.BaseUmbracoIndexer.PerformIndexRebuild() +80
   Examine.LuceneEngine.Providers.LuceneIndexer.RebuildIndex() in x:\Projects\Examine\Examine\Projects\Examine\LuceneEngine\Providers\LuceneIndexer.cs:775
   UmbracoExamine.UmbracoContentIndexer.RebuildIndex() +53
   Umbraco.Web.WebBootManager.<InitializeResolvers>b__f() +129
   Umbraco.Core.Sync.DatabaseServerMessenger.Initialize() +593
   Umbraco.Core.Sync.DatabaseServerMessenger.Boot() +87
   Umbraco.Web.BatchedDatabaseServerMessenger.Startup() +186
   Umbraco.Web.BatchedDatabaseServerMessengerStartup.ApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext) +63
   Umbraco.Core.ApplicationEventHandler.OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext) +37
   Umbraco.Core.CoreBootManager.<Complete>b__a(IApplicationEventHandler x) +219
   Umbraco.Core.EnumerableExtensions.ForEach(IEnumerable`1 items, Action`1 action) +141
   Umbraco.Core.CoreBootManager.Complete(Action`1 afterComplete) +282
   Umbraco.Web.WebBootManager.Complete(Action`1 afterComplete) +62
   Umbraco.Core.UmbracoApplicationBase.StartApplication(Object sender, EventArgs e) +234
   Umbraco.Core.UmbracoApplicationBase.Application_Start(Object sender, EventArgs e) +34

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +9918157
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +118
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +172
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +336
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +296

[HttpException (0x80004005): Exception has been thrown by the target of an invocation.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9932052
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34274