Event ID 2424 and 'The Parameter is incorrect'

Event Type: Error
Event Source: Windows SharePoint Services 3 Search
Event Category: Gatherer
Event ID: 2424
Description: The update cannot be started because the content sources cannot be accessed. Fix the errors and try the update again.

Context: Application 'Search', Catalog 'index file on the search server Search'


Based on the number of results returned in any web search of this error will tell you that this is a very common error. Luckily there are a few solutions. In order of likeliness to solve your problem:

1. Do not use local server accounts (i.e. network service) to run search. Use a domain user account with rights to SharePoint
2. Set the search content access account to be the same as the search service account
3. Add the registry key mentioned in this article: http://support.microsoft.com/kb/896861 (note: this assumes that you use host headers and are also seeing event 2436)



In my case, I've seen this error even after performing the above. However, the problem was actually that we had too many content sources crawling at the same time. Having multiple content sources crawling will severely limit the performance, but I've noticed that if you have 3 or more content sources crawling at the same time you can get this error in the event logs. You may also notice 'The parameter is incorrect' in the crawl logs.

So what do you do to solve this?

Schedule your crawls so that you don't have multiple crawls overlapping.