NullReferenceException when passing dialog name as variable to Microsoft.BeginDialog

Version

4.14.1

Describe the bug

When trying to start a dialog passing its name as a variable to Microsoft.BeginDialog, SDK throws a NullReferenceException. This is because the name is resolved at runtime and, when DialogContext.FindDialog tries to resolve dialog by name, it doesn’t find it in its property Dialogs

To Reproduce

Steps to reproduce the behavior:

1. Create a new bot using Composer
2. Create a dialog named A
3. In a trigger of your choice, do the following:
   • assign to a variable (e.g.: turn.dialogToStart) the string A (the name of the dialog to be started)
   • insert BeginDialog passing as dialog name =turn.dialogToStart
4. Start the bot and activate the trigger as per point 3. You should have a NullReferenceException

Expected behavior

Dialog should be added dynamically to DialogContext.Dialogs list when its name is resolved

Additional context

• Using BotFramework Composer version 2.1.2

[gabog]

Thanks for the comment @MatteoMilanese, @sw-joelmut, can you please see if you can repro the issue described above in your environment. If you do, please create a new issue so we can track it as a different PR (please add a reference to this issue in the new issue so we can track it in github too).

Thanks

[MatteoMilanese]

@gabog @sw-joelmut With respect to the PR #6338 that closed this issue, we encountered some problems with scalability as described in this comment above that doesn’t seem to be taken into account. To reproduce it, you can start dynamically a multi-turn dialog and, in the middle of the dialog, restart the bot. Of course you will need something like a CosmosDB emulator.

This, should simulate a scenario in which the conversation is continued on a different Azure Web App instance that has never dynamically started that dialog.