Ive got an Umbraco 7.xx which suddenly throws this error. I'm not directly using Examine but I'm aware that some of the inner Umbraco uses Examine. The site have run for ages without any access errors but suddenly it started.

Just before the error we had uploaded some images to the Media section.

When I do this:

if (profile.profileImage > 0) {
          var profileImage = Umbraco.Media(profile.profileImage); // EXCEPTION THROWN HERE
          profileImageUrl = profileImage.GetCropUrl("umbracoFile","Box200x200");
         profileImageName = profileImage.Name;
}

... an execption is thrown. This is from the log.

2014-10-23 07:39:53,019 [6] ERROR Umbraco.Core.UmbracoApplicationBase - [Thread 22] An unhandled exception occurred
System.UnauthorizedAccessException: Access to the path 'C:\website\App_Data\TEMP\ExamineIndexes\Internal\Index\segments.gen' is denied.
   at Lucene.Net.Store.SimpleFSDirectory.OpenInput(String name, Int32 bufferSize)
   at Lucene.Net.Index.SegmentInfos.FindSegmentsFile.Run(IndexCommit commit)
   at Lucene.Net.Index.DirectoryReader.Open(Directory directory, IndexDeletionPolicy deletionPolicy, IndexCommit commit, Boolean readOnly, Int32 termInfosIndexDivisor)
   at Examine.LuceneEngine.Providers.LuceneSearcher.ValidateSearcher(Boolean forceReopen)
   at UmbracoExamine.UmbracoExamineSearcher.GetSearchFields()
   at UmbracoExamine.UmbracoExamineSearcher.CreateSearchCriteria(String type, BooleanOperation defaultOperation)
   at Umbraco.Web.PublishedCache.XmlPublishedCache.PublishedMediaCache.GetUmbracoMedia(Int32 id)
   at Umbraco.Web.PublishedCache.ContextualPublishedCache`1.GetById(Boolean preview, Int32 contentId)
   at Umbraco.Web.PublishedContentQuery.DocumentById(Int32 id, ContextualPublishedCache cache, Object ifNotFound)
   at ASP._Page_Views_Partials_background_image_cshtml.Execute() in c:\Website\Views\Partials\background-image.cshtml:line 15
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.Html.RenderPartialExtensions.RenderPartial(HtmlHelper htmlHelper, String partialViewName)
   at ASP._Page_Views_MasterLayout_cshtml.Execute() in c:\Website\Views\MasterLayout.cshtml:line 102
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.WebPages.WebPageBase.Write(HelperResult result)
   at System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action`1 body)
   at System.Web.WebPages.WebPageBase.PopContext()
   at Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1a.b__17()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
   at System.Web.Mvc.Controller.<>c__DisplayClass1d.b__19()
   at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.b__0()
   at System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar)
   at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__3(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass4.b__3(IAsyncResult ar)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

The solution

We couldnt apply the needed access as the file seemed locked. We stopped the app pool and booted the server and startet app pool again. Still locked. 

Stopped the pool, restarted server and applied the  apparently missing access to the app pool identity. And it worked. 

Question remains.