Staff.Wiki uses the Lucene search engine, which is the same search engine used by the likes of Amazon for their Elastic search service.

If files have been moved around the file system manually, or an upgrade was not installed correctly, it may be possible that the search index can get corrupted. If this happens it is recommended to force the system to reconstruct the index, which usually only takes a minute or two.

Note: This operation must be performed by a system administrator who has access to the server.

It is recommended that you do this outside of regular usage hours, if possible.

On the server machine, go to the folder where Staff.Wiki is installed.

In there, go to the Files subfolder. You should see a file called searchindexstat48.dat. Delete this file (you can move it somewhere else if you prefer).

Next, restart the server. You can do this by following the instructions here, or from the IIS console.

For about 5 minutes (depending on the size of the wiki) the search index will not function while it is rebuilt (an error will display). Once the file searchindexstat.dat reappears in that folder, then the search index has been fully rebuilt and will be accessible from the web interface.