That happens when the command line is wrong. In your case it seems to be the --source parameter. It's either a local VMID or an IP:ZPool with an optional path.
Ok I think I found the issue. I had manually edited storage.cfg file which did not cause any issue. But then I tried adding a temp storage and deleting it from GUI to update strorage.cfg file as pve like it to then tried command, voliaaa it is running fine.
I think, somehow storage.cfg file must not be edited manually from ssh.