Failed to create virtual server : Failed to lock file /etc/passwd after 5 minutes. Last error was : Locked by PID 21363

I got this every time when i am creating new server or delete any server

Failed to create virtual server: Failed to lock file /etc/passwd after 5 minutes. Last error was : Locked by PID 21363

anyone can help me what should i do

i got this result for this command:
find /etc -name “*.lock”

/etc/gshadow.lock
/etc/group.lock
/etc/aliases.lock
/etc/passwd.lock
/etc/webmin/virtual-server/everyone/161043241333515.lock
/etc/shadow.lock
/etc/postfix/virtual.lock
/etc/postfix/bcc.lock
/etc/opendkim.conf.lock
/etc/apache2/mods-available/ssl.conf.lock
/etc/.pwd.lock

Operating system: Ubuntu
OS version: 18.04

The only useful information is what process that PID belongs to. That’s what’s hanging onto the lock.