I am working on an enterprise wiki site collection inside SharePoint 2013, and sometimes especially when modifying the wiki page name , users will get the following exception :-    I checked the logs and i find the following error "UserAgent not available, file operations may not be optimized. ... ". so can anyone adivce on this please? Thanks  Edit   Here is the log file uploaded to onedrive after enabling verbose logging , correlation id = 4bce009d-3c69-c0b7-30fc-0153080d3219 :-    i found the following 2 exceptions inside the log file :-   04/27/2015 12:51:36.38*   w3wp.exe (0x4640)                           0x225C  SharePoint Foundation           Files                           ak8dj   High        ...ecutionStep.Execute()     at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)     at System.Web.HttpApplication.PipelineStepManager.ResumeSteps(Exception error)     at System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext context, AsyncCallback cb)     at System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context)     at System.Web.Hosting.PipelineRuntime.ProcessRequestNotificationHelper(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags)     at System.Web.Hosting.PipelineRuntime.ProcessRequestNotification(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags)     at System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompl...  4bce009d-3c69-c0b7-30fc-0153080d3219 04/27/2015 12:51:36.49    w3wp.exe (0x4640)                           0x225C  SharePoint Foundation           Runtime                         tkau    Unexpected  System.NullReferenceException: Object reference not set to an instance of an object.    at Microsoft.SharePoint.Publishing.WssObjectCache.RemoveItemFromCache(Guid webId, Guid itemGuid, Boolean isList)     at Microsoft.SharePoint.Publishing.WssObjectCache.HandleChanges(SPChangeCollection changes)     at Microsoft.SharePoint.Publishing.CacheManager.CheckForChanges(SPSite site, Boolean forceGetChanges)     at Microsoft.SharePoint.Publishing.CacheManager.GetManager(SPSite site, Boolean useContextSite, Boolean allowContextSiteOptimization, Boolean refreshIfNoContext)
I have two sites that were originally migrated from SPS2003.  It worked well in SharePoint 2007 and even on SharePoint 2010,  however when we migrated it to SharePoint 2013,  the home page throws following errors on the ULS Log.     5/24/2013 09:57:46.62  w3wp.exe (0x0D50)   0x1D24  SharePoint Foundation   Files   ak8dj   High   UserAgent not available, file operations may not be optimized.    at Microsoft.SharePoint.SPFileStreamManager.CreateCobaltStreamContainer(SPFileStreamStore spfs, ILockBytes ilb, Boolean copyOnFirstWrite, Boolean disposeIlb)     at Microsoft.SharePoint.SPFileStreamManager.SetInputLockBytes(SPFileInfo&amp; fileInfo, SqlSession session, PrefetchResult prefetchResult)        05/24/2013 09:57:46.62 w3wp.exe (0x0D50)   0x1D24  SharePoint Foundation   Cobalt  ajoii   Medium   Mapping Store error to Cobalt error. [Store Error: System.NullReferenceException: Object reference not set to an instance of an object.     at Microsoft.SharePoint.CoordinatedStreamBuffer.SPCoordinatedStreamBufferFactory.CreateFromDocParams(SqlSession session, Guid guidSiteId, Int32 cbContent, Nullable1 parentId, Guid docId, Nullable1 level, SPChunkedArray`1 rgbContent, Byte[] rgbRbsId, Int64 bsn, Byte partition, Int32 pageSize, Boolean bStartFilling)        05/24/2013 09:57:46.62 w3wp.exe (0x0D50)   0x1D24  SharePoint Foundation   Cobalt  aintx   High    Failed in CobaltStream.LockBytes: ErrorException --- Error: Unknown (Win32=0x80004003) --- Error message: System.NullReferenceException: Object reference not set to an instance of an object.     at Microsoft.SharePoint.CoordinatedStreamBuffer.SPCoordinatedStreamBufferFactory.CreateFromDocParams(SqlSession session, Guid guidSiteId, Int32 cbContent, Nullable1 parentId, Guid docId, Nullable1 level, SPChunkedArray`1 rgbContent, Byte[] rgbRbsId, Int64 bsn, Byte partition, Int32 pageSize, Boolean bStartFilling)     at         05/24/2013 09:57:46.64 w3wp.exe (0x0D50)   0x1D24  SharePoint Foundation   Files   ak8dj   High    UserAgent not available, file operations may not be optimized.    at Microsoft.SharePoint.SPFileStreamManager.CreateCobaltStreamContainer(SPFileStreamStore spfs, ILockBytes ilb, Boolean copyOnFirstWrite, Boolean disposeIlb)     at Microsoft.SharePoint.SPFileStreamManager.SetInputLockBytes(SPFileInfo&amp; fileInfo, SqlSession session, PrefetchResult prefetchResult)     at         05/24/2013 09:57:46.64 w3wp.exe (0x0D50)   0x1D24  SharePoint Foundation   Database    ab1a9   High    Failed to get document content data. System.NullReferenceException: Object reference not set to an instance of an object.     at Microsoft.SharePoint.CoordinatedStreamBuffer.SPCoordinatedStreamBufferFactory.CreateFromDocParams(SqlSession session, Guid guidSiteId, Int32 cbContent, Nullable1 parentId, Guid docId, Nullable1 level, SPChunkedArray`1 rgbContent, Byte[] rgbRbsId, Int64 bsn, Byte partition, Int32 pageSize, Boolean bStartFilling)     at   I could not find any materials related to this on the internet,  I am not even sure if it has to do something with SPS2003 compatibility.  Any help pointers?
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