【问题说明】
重启vsftpd服务失败：
[root@data ~]# systemctl restart vsftpd
Job for vsftpd.service failed. See 'systemctl status vsftpd.service' and 'journalctl -xe' for details.
【查看日志】
首先，根据提示，查看vsftpd的进程状态，提示启动失败，code=exited, status=2：
[root@data ~]# systemctl status vsftpd.service
vsftpd.service - Vsftpd ftp daemon
Loaded: loaded (/usr/lib/systemd/system/vsftpd.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since 二 2019-03-12 11:25:39 CST; 1 day 5h ago
Process: 23209 ExecStart=/usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf (code=exited, status=2)
Main PID: 988 (code=killed, signal=TERM)
3月 12 11:25:39 qin systemd[1]: Starting Vsftpd ftp daemon...
3月 12 11:25:39 qin systemd[1]: vsftpd.service: control process exited, code=exited status=2
3月 12 11:25:39 qin systemd[1]: Failed to start Vsftpd ftp daemon.
3月 12 11:25:39 qin systemd[1]: Unit vsftpd.service entered failed state.
3月 12 11:25:39 qin systemd[1]: vsftpd.service failed.
其次，根据提示，查看journalctl -xe的内核日志和应用日志：
[root@data ~]# journalctl -xe
--
-- Unit user-0.slice has begun shutting down.
3月 13 16:08:29 qin rhnsd[1016]: /etc/sysconfig/rhn/systemid does not exist or is unreadable
3月 13 16:12:27 qin sshd[25906]: Accepted password for root from 172.16.*.* port 45676 ssh2
3月 13 16:12:27 qin systemd[1]: Created slice user-0.slice.
-- Subject: Unit user-0.slice has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit user-0.slice has finished starting up.
--
-- The start-up result is done.
3月 13 16:12:27 qin systemd[1]: Starting user-0.slice.
-- Subject: Unit user-0.slice has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit user-0.slice has begun starting up.
3月 13 16:12:27 qin systemd-logind[700]: New session 136 of user root.
-- Subject: A new session 136 has been created for user root
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- Documentation: http://www.freedesktop.org/wiki/Software/systemd/multiseat
--
-- A new session with the ID 136 has been created for the user root.
--
-- The leading process of the session is 25906.
3月 13 16:12:27 qin systemd[1]: Started Session 136 of user root.
-- Subject: Unit session-136.scope has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-136.scope has finished starting up.
--
-- The start-up result is done.
3月 13 16:12:27 qin systemd[1]: Starting Session 136 of user root.
-- Subject: Unit session-136.scope has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-136.scope has begun starting up.
3月 13 16:12:27 qin sshd[25906]: pam_unix(sshd:session): session opened for user root by (uid=0)
3月 13 16:20:01 qin sz[25937]: [root] vsftpd.conf/ZMODEM: 5075 Bytes, 62389 BPS
3月 13 16:28:40 qin sz[25953]: [root] vsftpd.conf/ZMODEM: 5075 Bytes, 428956 BPS
【解决方法参考】
方法一，vsftpd默认用的21端口被占用，关掉占用进程，以释放21端口：
命令1，查看21端口使用情况：
[root@data ~]# netstat -anp|grep 21
如果有进程在使用21端口，可以用命令2，关掉该进程：
[root@data ~]# kill PID（占用21端口的进程PID）
方法二，当前网络环境不支持IPv6，将配置文件/etc/vsftpd/vsftpd.conf中的listen_ipv6=YES配置为listen_ipv6=NO，或者在该行前用#注释掉；
命令1：vi /etc/vsftpd/vsftpd.conf
命令2：找到listen_ipv6=YES所在行，点击i（vi编辑器里的insert编辑）编辑，关闭或注释掉；
命令3：点击Esc，:wq保存即可。
方法三，虚拟用户配置文件中，文件名与虚拟用户名不一致导致，修改为一致即可。
如果有其他方法，欢迎互相分享难题，交流进步！
附/etc/vsftpd/vsftpd.conf：
# Example config file /etc/vsftpd/vsftpd.conf
#
# The default compiled in settings are fairly paranoid. This sample file
# loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd.conf.5 for all compiled in defaults.
#
# READ THIS: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's
# capabilities.
#
# Allow anonymous FTP? (Beware - allowed by default if you comment this out).
anonymous_enable=YES
#
# Uncomment this to allow local users to log in.
# When SELinux is enforcing check for SE bool ftp_home_dir
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# if your users expect that (022 is used by most other ftpd's)
local_umask=022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# has an effect if the above global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
# When SELinux is enforcing check for SE bool allow_ftpd_anon_write, allow_ftpd_full_access
#anon_upload_enable=YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# Activate logging of uploads/downloads.
xferlog_enable=YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES
#
# If you want, you can arrange for uploaded anonymous files to be owned by
# a different user. Note! Using "root" for uploaded files is not
# recommended!
#chown_uploads=YES
#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/xferlog
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
xferlog_std_format=YES
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120
#
# It is recommended that you define on your system a unique user which the
# ftp server can use as a totally isolated and unprivileged user.
#nopriv_user=ftpsecure
#
# Enable this and the server will recognise asynchronous ABOR requests. Not
# recommended for security (the code is non-trivial). Not enabling it,
# however, may confuse older FTP clients.
#async_abor_enable=YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# the request. Turn on the below options to have the server actually do ASCII
# mangling on files when in ASCII mode.
# Beware that on some FTP servers, ASCII support allows a denial of service
# attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd
# predicted this attack and has always been safe, reporting the size of the
# raw file.
# ASCII mangling is a horrible feature of the protocol.
#ascii_upload_enable=YES
#ascii_download_enable=YES
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# useful for combatting certain DoS attacks.
#deny_email_enable=YES
# (default follows)
#banned_email_file=/etc/vsftpd/banned_emails
#
# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
# (Warning! chroot'ing can be very dangerous. If using chroot, make sure that
# the user does not have write access to the top level directory within the
# chroot)
#chroot_local_user=YES
#chroot_list_enable=YES
# (default follows)
#chroot_list_file=/etc/vsftpd/chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled by
# default to avoid remote users being able to cause excessive I/O on large
# sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# the presence of the "-R" option, so there is a strong case for enabling it.
#ls_recurse_enable=YES
#
# When "listen" directive is enabled, vsftpd runs in standalone mode and
# listens on IPv4 sockets. This directive cannot be used in conjunction
# with the listen_ipv6 directive.
listen=NO
#
# This directive enables listening on IPv6 sockets. By default, listening
# on the IPv6 "any" address (::) will accept connections from both IPv6
# and IPv4 clients. It is not necessary to listen on *both* IPv4 and IPv6
# sockets. If you want that (perhaps because you want to listen on specific
# addresses) then you must run two copies of vsftpd with two configuration
# files.
# Make sure, that one of the listen options is commented !!
listen_ipv6=YES
pam_service_name=vsftpd
userlist_enable=YES
tcp_wrappers=YES
use_localtime=YES
reverse_lookup_enable=NO
方法四 ，根据上提示：/etc/vsftpd/vsftpd.conf 有问题，看来看去也没发现错误，几遍重启之后，觉可能能是文件里有空格，因为上次修改/etc/vsftpd/vsftpd.conf这个文件是，一不小心整只手按到了键盘上，我也不知道动了哪些字，所以就开始检查这个文件里面的空格 以及文件格式多看看：
通过以上方法大家可以试试，希望能帮助到大家！！！