Migration failing when attempting to load previous manifest

[alexhellenberg]

MigrationManifestSerializer().load(os.path.join(os.path.dirname(os.path.abspath(file)), 'manifest.json')) returns the following error:

result = self._dotnet.LoadAsync(path, cancellation_token).GetAwaiter().GetResult()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
System.MissingMethodException: Constructor on type 'Tableau.Migration.TableauInstanceTypeNotSupportedException' not found.

and will not run when 'manifest.json' exists in the directory. Runs fine when the 'manifest.json' file does not exist.