The SharePoint item being crawled returned an error when requesting data from the web service. (Error from SharePoint site: *** Index was outside the bounds of the array.)

We have below errors when we run the search crawl in the SharePoint 2010 farm.

1) The SharePoint item being crawled returned an error when requesting data from the web service. (Error from SharePoint site: *** Index was outside the bounds of the array.)
2) The object was not found.
3) The server is unavailable and could not be accessed. The server is probably disconnected from the network.
4) This item could not be crawled because the repository did not respond within the specified timeout period. Try to crawl the repository at a later time, or increase the timeout value on the Proxy and Timeout page in search administration. You might also want to crawl this repository during off-peak usage times.
5) The docfile has been corrupted
6) There is more than one match for your term. Please disambiguate which term you would like to use.
7) The SharePoint item being crawled returned an error when requesting data from the web service. ( Error from SharePoint site: *** Root element is missing. )

We have fixed all issues by following below steps which are recommended by Microsoft

1. Take a snapshot of SharePoint Servers and SQL servers.

2. Take back up of all the content databases.
3. Download OCT CU 2011 (http://support.microsoft.com/kb/2596505 )
4. Install this CU On SharePoint Server.
5. Run SharePoint Products & Configuration Wizard.
6. Once completed Run the full crawl.

Still if you see the errors you might have some problem with your managed metadata.

For example when you restore your SharePoint site to development environment from production, you should restore managed metadata service database as well. Then only metadata works fine and it will synchronize with SharePoint site database.

Update Managed Metadata service database (to fix invalid term set)

1) Take a backup of production managed metadata service database
2) Restore to your development server or where ever you are working
3) Go to central admin site, create a new managed metadata service or update existing metadata service database name field with your recently restored database name.
4) If you have created a new metadata service, you have to check the checkbox of that newly created service to the web application.

Central Administration>Application Management>Service Applications>Manage service applications

>select Managed Metadata Service> select Properties from ribbon

Update your “database name” (the one recently you have taken backup and restored from production) field as shown in screenshot