I hit this error trying to import some VMs into OVM
To get more detail I tried the command from the ocmmand line
curl -v "ftp://root:email@example.com/var/tmp/taxud-disk1.vmdk"
* About to connect() to 192.168.8.192 port 21
* Trying 192.168.8.192... connected
* Connected to 192.168.8.192 (192.168.8.192) port 21
< 220 (vsFTPd 2.0.5) > USER root
< 331 Please specify the password. > PASS blahroot
< 230 Login successful. > PWD
< 257 "/root" * Entry path is '/root' > CWD var
< 550 Failed to change directory. * Server denied you to change to the given directory * Connection #0 to host 192.168.8.192 left intact curl: (9) Server denied you to change to the given directory > QUIT
< 221 Goodbye.
This is because the pathname I have given is relative, rather than absolute, so I was unknowingly trying to change directory to /root/var/tmp which did not exist.
To give an absolute pathname, you need an extra slash