My web project was not being packaged correctly. The nuget only contained the assemblies from bin folder, and those were placed in the root of the package - no actual bin folder was created. All the other files from the project that are required for a valid web application were not packaged. It took me quite a while to finally determine the cause - I didn’t have a web.config file. The project had a web.config referenced, I just didn’t have an actual file on disk. When I created a file, the package was correctly created. Even if the project does not reference the web.config, the nuget will only be properly created if a web.config exists on disk.
I don’t see a reason why correct package generation should be dependent on the existance of web.config. Please remove this dependency. The project properties should be enough to figure out that this is a web application.
(I found http://help.octopusdeploy.com/discussions/problems/10977-octopack-as-web-project-without-webconfig which is the same problem, but that discussion is closed.)