When using Converge with Umbraco V9, please be aware of the following setting. Converge can be used to create or update document types, which in turn are used to create Models Builder models. It is therefore possible that Converge will create code files in your project when the document types are created or updated.
As Umbraco V9 is now built on ASP .NET Core, this could trigger a rebuild of your project while Converge is running, causing it to crash. Please ensure the following setting in Visual Studio (Tools-->Options) is not set to "Auto build on browser request (IIS only)".