Troubleshooting: Request errors when checking out large shopping carts using Microsoft IIS

If your shopping cart contains a large amount of order items, you might encounter request errors when checking out.


If you are using the Microsoft IIS Web server, you might encounter errors similar to the following errors when checking out with large shopping carts:
  • 414 Request URL too long
  • 400 Bad Request - Request Too Long

When the single shipment button is clicked on the shipping and billing page of an order that contains many order items, the encryption of the orderitem_id causes the krypto string to become very long.


To resolve this issue, you must increase the default header size limit:
  1. Open the registry.
  2. Create the following DWORD decimal values under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters:

    These replacement values are double the default values. You can enter a value more suited towards your environment where necessary.

  3. Restart the HTTP services and related IIS services.

For more information, see Microsoft support: Http.sys registry settings for IIS.