How to debug “Vagrant cannot forward the specified ports on this VM” message

Question

I\'m trying to start a Vagrant instance and getting the following message:

Vagrant cannot forward the specified ports on this VM, since they
would collide wi         


        

Answer 1

Also note that (in Vagrant 1.6.4 at least) there is the folder ~/.vagrant.d/data/fp-leases, with files having names like 8080, 8081 etc. Erasing this folder contents helped me just now.