Had an interesting problem the other day where, upon examining the Search Administration service, it was discovered that no content was being indexed. Any existing content in the index had been removed en masse one night.
Neither restarting nor resetting the index, common ways to fix search errors, did anything. Any new indexing attempts would yield errors saying that the content could not be indexed because access was denied. The content access account did not have any issues with it, though an attempt at updating it for the sake of completeness yielded the following error on the Search Administration page:
The search service is currently offline. Visit the Services on Server page in SharePoint Central Administration to verify whether the service is enabled. This might also be because an indexer move is in progress.
Still, the error did not point to anything of use. According to the Search Administration page the search server was healthy and running, with everything showing green checkmarks (the only clue that something was amiss was that there were no searchable items).
An examination of the SharePoint ULS logs showed the following:
mssearch.exe SharePoint Server Search Crawler:Gatherer Service High Failed to encrypt new master key [gthrapp.cxx:4149] search\native\gather\gthrsvc\gthrapp.cxx
mssearch.exe SharePoint Server Search Crawler:Gatherer Service High Failed to write master key to registry [gthrapp.cxx:4094] search\native\gather\gthrsvc\gthrapp.cxx
Unfortunately these seems to have been an unique situation – no one else seems to have had this problem (that I found).
Further investigation into the Windows Event Logs yielded this for the search service service account:
The LoadUserProfile call failed with the following error:
Access is denied.
Finally! A clue! Turns out the profile for the search service account was corrupt. By deleting the corrupt user profile (which showed up as “Backup” on the User Profile management dialog (Computer > Properties > Advanced > User Profiles) and restarting the search service, our search finally was able to reindex our content!