I got this error when run the install script
Install-SPSolution –Identity MySolution.wsp –WebApplication http://mywebapplication –GACDeployment
even my solution includes a feature whose scope is webapplication.
it will not have problem if I deploy to all web applications but I do want to only deploy to a particular web application.
After search around, I found
Right click on the project and press F4. This will open the project properties window. From there Select the Assembly Deployment type From GlobalAssemblyCache to Web Application as shown in the figure below.
then you can deploy it to the web application now.