Vagrant error : Failed to mount folders in Linux guest

Question

I have some issues with Vagrant shared folders, my base system is Ubuntu 13.10 desktop.

I do not understand why I have this error is something that is not right conf

Answer 1

I arrived at this page whilst looking for the same error message. For me the cause was different: I had ran a yum update on the system that installed a new kernel. The guest additions where out of date so it couldn't load them.

I rebuilt them with

sudo /etc/init.d/vboxadd setup 

And a vagrant reload later my guest was up and running again.

I'm just adding it here in case someone else gets here the same way I did.

Edit (Per KCD's comment):
It is possible that you get an error saying:

The headers for the current running kernel were not found

This can be resolved by installing kernel-devel (yum install kernel-devel)