While populating more than thousands of products, I am getting below error in asp.net

The maximum number of form, query string, or posted file items has already been read from the request. To change the maximum allowed request collection count from its current value of 1000, change the "aspnet:MaxHttpCollectionKeys" setting. See http://go.microsoft.com/fwlink/?LinkId=238386 for more information.

I tried changing code in web.config also with and set maxhttpcollectionkeys as 5000 also but still getting above error.

Please suggest solution.

Thank you.