One of the common problems I’ve seen with Microsoft SharePoint is the loss of search functionality, and I’ve found a lot of different theories and possible solutions.  I’ve tried to combine the various ideas into a step by step troubleshooting strategy.  Pleae note that this only applies if you’ve had a working earch service in the past – if not, you need to enable the search service before you do anything else!

Symptoms

Individual sites and site collections respond to any search query with no results.

The event log on the SharePoint Server shows Event  ID 2436 – The start address <site url> cannot be crawled.

The crawl log within SharePoint says that the site cannot be crawled and has been deleted from the gatherer.

Possible Resolutions

First, disable loopback checking on IIS, if you haven’t already.  This is one of the most common causes of the problem, and if it isn’t done, means that you WILL experience the problem sooner or later anyway.  To disable loopback checking, you need to make a registry change and restart your server, so schedule it for a quiet time.

Follow these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. In Registry Editor, locate and then click the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Quit Registry Editor, and then restart your computer.

Second, check the permissions on the search service.  It sounds silly, but it is easy to sometimes use an account that doesn’t have access rights to actually crawl the sites!  Don’t get too involved with this, however – if it looks right, it probably is.  Its easy to waste days checking odd possibilities of access rights, but if this is the cause, its normally pretty obvious!

Third, ensure that there is a site at the top level of the web application.  This sounds ludicrous, but I’ve seen systems spring into life after a blank site is deployed at the root of the website.  Its easy to check, and easy to fix.  Many people won’t have seen this, as it’s pretty common practise to deploy self service site creation in the root url.  I’ve particularly seen this on systems after an SP2 MOSS and WSS install.  If a 404 error is received on the root url, all the other sites won’t be crawled.