Error when deploying a Visual Web Part:
use the force attribute to explicitly re-install the feature.
Is the force not with me? How do i use the force?
Always Force Install to True in for your feature. (Assuming you are using Visual Studio)...Check the feature property window and you should see this option!
If you are using PowerShell, you can also use :
$sln = Add-SPSolution mySolution.wsp Install-SPSolution -Identity mySolution.wsp -GACDeployment -Force