Update from 1.9 to 2.0 with fail

/etc/init.d/pve-cluster stop
Stopping pve cluster filesystem: pve-cluster apparently not running.

/etc/init.d/pve-cluster start
Starting pve cluster filesystem : pve-clusterfuse: mountpoint is not empty
fuse: if you are sure this is safe, use the 'nonempty' mount option
[main] crit: fuse_mount error: No such file or directory
[main] notice: exit proxmox configuration filesystem (-1)
(warning).
 
/etc/init.d/pve-cluster stop
Stopping pve cluster filesystem: pve-cluster apparently not running.

/etc/init.d/pve-cluster start
Starting pve cluster filesystem : pve-clusterfuse: mountpoint is not empty

Seems there is some old data inside /etc/pve - please try to remove that, for example:

# mv /etc/pve /etc/pve.mybackup
# mkdir /etc/pve

Then try again:

# /etc/init.d/pve-cluster start