Use this command instead.
pscp -h host.txt -l <username> -Av terminal.sh /tmp/
I think you are getting the error because of permission issue.(Assuming that there is actually a directory under /
named Desktop)
Or if you want to copy that file to home directory of a user, then you might need to cross check the destination path specified in your command.
Normally user home directories are under /home/
directory. So if you haven't changed your client machine's home directory,you can try the following command to copy the file.
pscp -h host.txt -l <username> -Av terminal.sh /home/<username>/Desktop/
If the above given command doesn't solve your problem, you can generate error log using the following command. So that you can understand whether the issue is due to file permission or authentication failure, etc.
pscp -h host.txt -e error -Av terminal.sh /Desktop/terminal.sh