Unable to update main FTP account password

Unable to update the main (default) FTP account password via control panel. The following error o
ccurred:
Attempting to modify nonexistent username
Couldn't delete previous ProFTPd user config file.

The issue is occurring due to the absence of password entry in the passwd.vhosts file.
#cd /etc/proftpd/
Server:/etc/proftpd#grep userName: passwd.vhosts
Server:/etc/proftpd#

This shows that password entry is missing in the /etc/proftpd/passwd.vhosts. Add the coresponding
entry from /etc/proftpd/userName.

The entry can be found from /etc/proftpd/userName
Server:/etc/proftpd#grep userName: userName
(example:- userName:$1$MAwZd0to$A8U6GQNGwkC0c7DA0P/7..:1697:1697:domainName:/home/userName:/nonexistent)

Add the above entry in /etc/proftpd/passwd.vhosts
Server:/etc/proftpd#cat >> passwd.vhosts
userName:$1$MAwZd0to$A8U6GQNGwkC0c7DA0P/7..:1697:1697:userName:/home/userName:/nonexistent