While doing a routine maintenance check on a system which is running Sitecore 8.1 Update 2 , I would start seeing series of errors related to path analyzer. The details of the issues are below
12008 09:55:52 FATAL [Path Analyzer](ApplicationContainer.GetInstance) Can’t create instance using path ”. Make sure the referred element is present in configuration
12008 09:55:52 ERROR Exception when executing agent pathAnalyzer/newMapAgent
Message: tree definition service
As such from the looks of it, it really does not explain in detail as to why the path analyzer instances are not being able register correctly.
<processor type="Sitecore.PathAnalyzer.Pipelines.Initialize.Loader, Sitecore.PathAnalyzer" />
<processor type="Sitecore.PathAnalyzer.Pipelines.Initialize.Loader, Sitecore.PathAnalyzer" patch:before="processor[@type='Sitecore.Pipelines.Loader.LoadHooks, Sitecore.Kernel']" />
Indeed this fix did work for me, Sitecore support also acknowledged that this issues is a defect in sitecore 8.1 Update 2 , please mention reference 99665 in the support ticket.
Please comment if you have further questions or tweet me @sjain_hi