Hello, 

I have installed Episerver Forms 4.0.0 to a site running Episerver CMS version 9.12.2. 

I can´t get the drag n drop functionality to work, i.e when you have the form elements in the right handed area and drag them into the Forms ElementsArea. I get this error:

2016-10-31 09:44:07,939 [125] EPiServer.Logging.Compatibility.LogManager+CompatibilityWrapper.Error(:0) - Unexpected error when updating property elementsArea
EPiServer.Core.EPiServerException: ContentReference: Input string was not in a correct format.
   at EPiServer.Core.ContentReference.Parse(String s)
   at EPiServer.Cms.Shell.Json.ContentAreaConverter.ReadJson(JsonReader reader, Type objectType, Object existingValue, JsonSerializer serializer)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.DeserializeConvertable(JsonConverter converter, JsonReader reader, Type objectType, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at EPiServer.Framework.Serialization.Json.JsonObjectSerializer.Deserialize(TextReader reader, Type objectType)
   at EPiServer.Cms.Shell.UI.Rest.ContentChangeManager.Deserialize(String value, Type type)
   at EPiServer.Cms.Shell.UI.Rest.ContentChangeManager.UpdateProperties(IDictionary`2 properties, IContent content)

I cannot find a solution for this, anyone one else with the same problem?

Update:

When I looked at the ajax request being made I found the contentLink attribute was missing from the dragndrop element.

{  
      "contentGroup":"",
      "name":"RangeElementBlock",
      "roleIdentities":[  

      ],
      "typeIdentifier":"episerver.forms.implementation.elements.rangeelementblock",
      "attributes":{  
         "data-contentgroup":""
      }
   },