If your application needs more time to execute, you might see the below error in your site:

Server Error in '/' Application.
Request timed out.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Request timed out.

To fix this, edit your web.config and increase the execution timeout value under systems.web tag.

<system.web>

<httpRuntime executionTimeout="x"/>

</system.web>

</configuration>

Where x is the execution timeout value in seconds.