centos7 cron job pam_limit linha inválida hard nproc ignorada

Estou recebendo o erro:

May 29 19:15:02 vps3.domain.com crond[19846]: pam_limits(crond:session): invalid line 'user3 hard nproc ' - skipped
May 29 19:15:02 vps3.domain.com crond[19846]: pam_limits(crond:sess:on): invalid line 'user4 hard nproc ' - skipped

A linha cron é:

* * * * * /usr/local/bin/php /home/user3/public_html/api/crons/cron-mailer.php

Eu tentei muitas soluções de pilhas e nada funciona.

Eu tentei:

1. Adicionando /etc/security/limits.conf

   raiz suave nproc 200000

   raiz difícil nproc 200000

2. sysctl1 -w fs.file-max=200000

A reinicialização do cron, mas ainda recebo os erros acimasystemctl status crond

Qual é a solução para este problema, já que não consigo executar nenhum cron?

Atualização: Conteúdo de /etc/security/limits.conf

# /etc/security/limits.conf
#
#This file sets the resource limits for the users logged in via PAM.
#It does not affect resource limits of the system services.
#
#Also note that configuration files in /etc/security/limits.d directory,
#which are read in alphabetical order, override the settings in this
#file in case the domain is the same or more specific.
#That means for example that setting a limit for wildcard domain here
#can be overriden with a wildcard setting in a config file in the
#subdirectory, but a user specific setting here can be overriden only
#with a user specific setting in the subdirectory.
#
#Each line describes a limit for a user in the form:
#
#<domain>        <type>  <item>  <value>
#
#Where:
#<domain> can be:
#        - a user name
#        - a group name, with @group syntax
#        - the wildcard *, for default entry
#        - the wildcard %, can be also used with %group syntax,
#                 for maxlogin limit
#
#<type> can have the two values:
#        - "soft" for enforcing the soft limits
#        - "hard" for enforcing hard limits
#
#<item> can be one of the following:
#        - core - limits the core file size (KB)
#        - data - max data size (KB)
#        - fsize - maximum filesize (KB)
#        - memlock - max locked-in-memory address space (KB)
#        - nofile - max number of open file descriptors
#        - rss - max resident set size (KB)
#        - stack - max stack size (KB)
#        - cpu - max CPU time (MIN)
#        - nproc - max number of processes
#        - as - address space limit (KB)
#        - maxlogins - max number of logins for this user
#        - maxsyslogins - max number of logins on the system
#        - priority - the priority to run user process with
#        - locks - max number of file locks the user can hold
#        - sigpending - max number of pending signals
#        - msgqueue - max memory used by POSIX message queues (bytes)
#        - nice - max nice priority allowed to raise to values: [-20, 19]
#        - rtprio - max realtime priority
#
#<domain>      <type>  <item>         <value>
#

#*               soft    core            0
#*               hard    rss             10000
#@student        hard    nproc           20
#@faculty        soft    nproc           20
#@faculty        hard    nproc           50
#ftp             hard    nproc           0
#@student        -       maxlogins       4

# End of file


*               soft    nofile         200000
*               hard    nofile         200000
*               soft    nproc          200000
*               hard    nproc          200000
root            soft    nofile         200000
root            hard    nofile         200000
root            soft    nproc          200000
root            hard    nproc          200000

Atualização 2: Arquivos em /etc/security/limit.d/

Conteúdo do 20-nproc.conf :

# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

*          soft    nproc     4096
root       soft    nproc     unlimited

Depois, há um arquivo para cada usuário com o conteúdo:

user1 hard nproc 
user1 hard nofile