InternalError: error CS0453

InternalError: error CS0453

  

Hello,

I have a mobile app and a web app that I am working on. I am trying to couple these two apps and implement a data sync between the two. The web app is acting as my data hub, so it is a dependency in my mobile app. I am trying to follow this example:

https://success.outsystems.com/Documentation/11/Developing_an_Application/Use_Data/Offline/Offline_Data_Sync_Patterns/Read%2F%2FWrite_Data_One-to-Many

However, I am getting stuck in the "Sync Companies Logic" step. Specifically, in the dictionary mapping. Within this server action they have an output variable "NewCompaniesIdMappings" which is of type Object. When I create this variable in my server action and try to publish I get this error:

Internal Error
Compilation Error.
ScreenServices.REST<app_name>_ActionSyncForms_Outputs.cs(25,16): error CS0453: The type 'object' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable<T>'
public object? outParamNewFormIdMappings;
c:\Windows\Microsoft.NET\Framework64\v4.0.30319\mscorlib.dll: (Location of symbol related to previous error)

From my point of view, every thing is exactly the same, so I can't understand why I am getting this error. Any ideas?

You can find the data sync patterns here: 

https://www.outsystems.com/forge/component/1638/Offline+Data+Sync+Patterns/

Also, if there is a better/easier way that I be coupling these applications please share your thoughts. Thanks!