Security accessibility of the overriding method must match the security accessibility of the method being overriden

My .net project was running fine. After updating it from .net 4.6 to 4.8 and MVC 4 - MVC5, following error occured:

System.TypeLoadException HResult=0x80131522 Message=Inheritance security rules violated while overriding member: 'DevExpress.Web.Mvc.MaskAttribute.System.Web.Mvc.IClientValidatable.GetClientValidationRules(System.Web.Mvc.ModelMetadata, System.Web.Mvc.ControllerContext)'. Security accessibility of the overriding method must match the security accessibility of the method being overriden. Source= StackTrace:

It will be very helpful if someone guide through this. Thank you.