Getting Value cannot be null. parameter name: source on release but not in debug

Question

I'm creating a Revit plugin that reads and writes modelinformation to a database, and it all works fine in debug mode, but when I release the project and run Revit with the plugin outside visual studio, I'm getting an error when the plugin tries to read data from the database.

The code runs on DocumenetOpened event and looks like this:

 public void application_DocumentOpenedEvent(object sender, DocumentOpenedEventArgs e)
    {
        UIApplication uiapp = new UIApplication(sender as Autodesk.Revit.ApplicationServices.Application);
        Document doc = uiapp.ActiveUIDocument.Document;



        //ModelGUID COMMAND
        var command = new ModelCheckerCommandExec();
        command.Execute(uiapp);

    }

It then fails on the following line:

ModelsList = (DatabaseHelper.ReadNonAsync<RevitModel>())
.Where(m => m.ModelGUID == DataStores.ModelData.ModelGUID).ToList();

In this code block that gets executed:

public class ModelCheckerCommandExec : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        return Execute(commandData.Application);
    }

    public Result Execute(UIApplication uiapp)
    {
        Document doc = uiapp.ActiveUIDocument.Document;

        Transaction trans = new Transaction(doc);
        try
        {
            trans.Start("ModelGUID");
            ModelGUIDCommand.GetAndSetGUID(doc);
            trans.Commit();

            var ModelsList = new List<RevitModel>();
            ModelsList = (DatabaseHelper.ReadNonAsync<RevitModel>()).ToList();//.Where(m => m.ModelGUID == DataStores.ModelData.ModelGUID).ToList(); // Read method only finds models the are similar to the DataStore.ModelDate.DBId;

            if (ModelsList.Count == 1)
            {

                trans.Start("DataFromDB");

                doc.ProjectInformation.Name = ModelsList[0].ProjectName;
                doc.ProjectInformation.Number = ModelsList[0].ModelNumber;
                doc.ProjectInformation.Status = ModelsList[0].ModelStatus;
                doc.ProjectInformation.IssueDate = ModelsList[0].ProjectIssueDate;
                doc.ProjectInformation.ClientName = ModelsList[0].ClientName;
                doc.ProjectInformation.Address = ModelsList[0].ProjectAddress;
                doc.ProjectInformation.LookupParameter("Cadastral Data").Set(ModelsList[0].ProjectIssueDate);
                doc.ProjectInformation.LookupParameter("Current Version").Set(ModelsList[0].CurrentVersion);
                doc.ProjectInformation.BuildingName = ModelsList[0].BuildingName;

                DataStores.ModelData.ModelManager1 = ModelsList[0].ModelManagerOne;
                DataStores.ModelData.ModelManager1Id = ModelsList[0].ModelManagerOneId;
                DataStores.ModelData.ModelManager2 = ModelsList[0].ModelManagerTwo;
                DataStores.ModelData.ModelManager2Id = ModelsList[0].ModelManagerTwoId;


                trans.Commit();
            }

            return Result.Succeeded;
        }
        catch (Exception ex)
        {
            TaskDialog.Show("Error", ex.Message);
            return Result.Failed;
        }
    }
}

The "ReadNonAsync" method is as follows:

public static List<T> ReadNonAsync<T>() where T : IHasId
        {

            using (var client = new HttpClient())
            {
                var result = client.GetAsync($"{dbPath}{Properties.Settings.Default.CompanyName}_{typeof(T).Name.ToLower()}.json?access_token={DataStores.IdToken.UserIdToken}").GetAwaiter().GetResult();
                var jsonResult = result.Content.ReadAsStringAsync().GetAwaiter().GetResult();

                if (result.IsSuccessStatusCode)
                {
                    var objects = JsonConvert.DeserializeObject<Dictionary<string, T>>(jsonResult);
                    List<T> list = new List<T>();

                    if (objects != null)
                    {
                        foreach (var o in objects)
                        {
                            o.Value.Id = o.Key;
                            list.Add(o.Value);
                        }
                    }

                    return list;
                }
                else
                {
                    return null;
                }
            }
        }

In the rest of my code I use a async Read method which works, so I'm wondering wether or not that's the issue, but Revit wont let me use an async method inside an Execute method.

How do I debug this issue correctly, and why could there be code working in debug that doesn't work in "live" versions?

Answer 1

I found a solution!

The issue: The reason for the error was that when I run the software in debug-mode, a file path of "xxx.txt" finds files in the solution folder, but when I run the software "xxx.txt" points to the folder of the software and not the .dll - So in my case it pointed to "c:\Program Files\Autodesk\Revit\2021".

The fix: Hard coding the path, or by getting the path of the executing .dll

Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)

Debugging/Troubleshooting: I found the issue by inserting dialogboxes with errormessages in all my try/catch statements.