I updated EPi and the EPi Commerce Manager from 7.5 to 7.8.6 on a test site. Everything seems to workfine, with one major exception concerning shipping methods in Commerce Manager.

When I go to Admin->Order System->Shipping->Shipping Methods and select a shipping method I created in 7.5 a red error message is shown at the top of the edit window: "Error during binding gateway settings: Object reference not set to an instance of an object." All fields in the editor look normal though. If I hit OK, an exception is thrown:

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   Mediachase.Commerce.Manager.Apps.Order.Tabs.ShippingMethodsHelper.ModifyMarkets(ShippingMethodRow shippingRow, ShippingMethodDto dto, DualList marketList) +210
   Mediachase.Commerce.Manager.Order.Shipping.Tabs.ShippingMethodEditSettings.SaveChanges(IDictionary context) +292
   Mediachase.Commerce.Manager.Core.Controls.EditViewControl.SaveChanges(IDictionary context) +279
   Mediachase.Commerce.Manager.Order.Shipping.ShippingMethodEdit.EditSaveControl_SaveChanges(Object sender, SaveEventArgs e) +730
   Mediachase.Commerce.Manager.Core.SaveControl.OnSaveChanges(Object sender, EventArgs e) +57
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +154
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3803

If I try to create a brand new shipping method, a similar exception is thrown as soon as I hit "New":

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[NullReferenceException: Object reference not set to an instance of an object.]
   Mediachase.Commerce.Manager.Order.Shipping.Tabs.ShippingMethodEditSettings.Bind(IEnumerable`1 selectedRows, IEnumerable`1 unselectedRows, DualList dualList) +14
   Mediachase.Commerce.Manager.Order.Shipping.Tabs.ShippingMethodEditSettings.BindForm() +321
   System.Web.UI.Control.LoadRecursive() +70
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Control.LoadRecursive() +189
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3177

The error message in the editing page suggests this has something to do with ShippingGateways, but I have no idea what the actual problem is. Has anyone seen anything like this, or have any suggestions?