error after press continue button for shipping methods

Invalid cast from 'System.String' to 'System.Collectins.Generic.List' 1[[Nop.Core.Domain.Shipping.ShippingOption, Nop.Core, Version=2.6.0.0, Culture=neutral, PublicKeyToken=null]]'

....some context?
Version, plugins, modifications to the pages?

M.Ang wrote:
version 2.60. i work with nopcommerce multistore but file with this error has no change from version 2.60 nopcommerce

I solve it! I updated Nop.Core.Domain.Shipping.ShippingOptions.cs, Nop.Core.CommonHelper.cs from nopcommerce2.60