"spawn id exp5 not open" Error when when scp'ing with an expect script - expect

Question

I have the an expect script that starts like the following:
#!/usr/bin/expect -f
set timeout 1200
set prompt {[#$] }
set server [lindex $argv 0]
set username [lindex $argv 1]
set password [lindex $argv 2]
set package [lindex $argv 3]
spawn scp -o StrictHostKeyChecking=no "$package" ${username}#${server}:~
expect {
timeout { send_user "\nscp connect time out\n"; exit 1 }
"*assword"
}
after 3000
send "$password\r"
# wait for upload complete
expect {
timeout { send_user "\nscp timeout\n"; exit 1 }
eof
}
....
close
It errors out with the following message after ~15 s:
send: spawn id exp5 not open
while executing
"send "$password\r""
What could be the reason for this? What does exp5 mean?
I have also tried removing the "after 3000" statement, but I get the same error.

Answer 1

The connection is closed by the time you get to the point where you send your password. I suspect that you don't need to enter a password for that server (ssh keys are set up?), and by the time 3 seconds has elapsed (after 3000), the file transfer is complete.
You can condense your script somewhat:
#!/usr/bin/expect -f
set timeout 1200
set prompt {[#$] }
lassign $argv server username password package
# if your expect version does not have `lassign`, stick to below
#set server [lindex $argv 0]
#set username [lindex $argv 1]
#set password [lindex $argv 2]
#set package [lindex $argv 3]
spawn scp -o StrictHostKeyChecking=no "$package" ${username}#${server}:~
expect {
timeout {send_user "\nscp time out\n"; exit 1}
"*assword" {send "$password\r"; exp_continue }
eof
}
This loses the distinction between connection timeout and transfer timeout though.