When creating a Sharepoint 2010 project in VB.NET and wanting to deploy an additional referenced assembly you cannot add a new project output assembly to the package.
To replicate the issue:
This error is then presented:
Cannot add a new project output assembly to the package.
The path is not of a legal form.
Any ideas on what the "path" is that is not "of a legal form"?
Not sure, but sounds like you are hitting same bug as as Andrew Connell