How to unmount NFS when server is gone?

You can use umount -f -l /mnt/myfolder, and that will fix the problem.

• -f – Force unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.)

• -l – Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)

^{Source:Linux Complete Command Reference}

try sudo umount -l {mountPoint} to do a "lazy unmount". Lets you move on with your life without waiting for the plumber to arrive.

In my case where umount -f did not work, umount -fr worked. -r argument remounts as read-only and then unmounts the folder.