ASP.NET::The timeout period

The timeout period elapsed prior to completion of the operation or the server is not responding.

try below options, set command timeout parameter to 0. It will execute till the end. By default it will timeout in 30 secs.

Using Code:

sqlCommand.CommandTimeout = 0;

Using Connection String: Check the timeout in connection string, try setting it to max...
data source="ServerName;initial catalog=DataBaseName;uid=ID;pwd=Password;Connect Timeout=120"

Using Sql Server:On the SQL Server also you can set timeout of a query. Check with SQL Server DBA's to know the Query time out set on servers.

Using IIS: On IIS also you have timeout setting. In IIS --> Website tab --> Connection time out box . Set the max timeout value (in secs) IIS should maintain idle connection .

check all these possibilities