You have a lingering connection to a no-longer-existent outlet. Double check this via the main storyboard file. What exactly you need to do is right click on each view to see if you got any outlets that are not being used? If yes, then simply remove that outlet.
Sometimes, when I vagrant up my dev environment, the below warning appears. Vagrant cannot forward the specified ports on this VM, since they would collide with some other application that is already listening on these ports. The forwarded port to 9200 is already in use on the host machine. So what we need to do is to list