Plesk Obsidian Web Admin Edition
Plesk Obsidian 18.0.30 Update #2
CentOS Linux 7.8

Tools and Settings & gt; Diagnose and Repair
Problem detected on web server and FTP server. Automatic repair does not fix it.

Checking for nginx ULIMIT value 1 domains have been found on server. Problem with nginx default limit for open files is possible Please check https://support.plesk.com/hc/articles/213938485 for details

The displayed URL is Not Found.

Detailed investigation

# plesk repair web -verbose

Checking Plesk version
  Installed Plesk version/build: 18.0.30 CentOS 7 1800200930.13
  Checking for custom configuration templates ....................... [OK]

Checking the JkWorkersFile directive in the Apache configuration .... [OK]

Checking associations between domains and IP addresses .............. [OK]

Checking for corrupted reference between IP collections and
IPaddresses ......................................................... [OK]

Checking for links between APS applications and subscriptions ....... [OK]

Checking for nginx ULIMIT value
  1 domains have been found on server. Problem with nginx default
  limit for open files is possible
  Please check https://support.plesk.com/hc/articles/213938485 for
  details ........................................................... [WARNING]

Checking for extra configurations in database not owned by any object
................................................................... [OK]

Checking the configuration of Apache modules ........................ [OK]

Checking web server configuration

  Reinstall SSL/TLS certificates and set the default certificate for all IP addresses? [Y/n]
    Reinstalling SSL/TLS certificates ............................... [OK]
    Applying the default SSL/TLS certificate to all IP addresses .... [OK]

  Repair web server configuration for all domains? [Y/n]
    Repairing web server configuration for all domains. This aspect
    can be used with individual domains ("plesk repair web
    example.com"), and on the server level ("plesk repair web") ..... [OK]

  Repair server-wide configuration parameters for web servers? [Y/n]
    Repairing server-wide configuration parameters for web servers .. [OK]

Checking the usage of PHP handlers .................................. [OK]

Checking for obsolete PHP-FPM configuration files ................... [OK]

Error messages: 0; Warnings: 1; Errors resolved: 0

#

Solutions

https://talk.plesk.com/threads/checking-for-nginx-ulimit-value-3-domains-have-been-found-on-server.357644/

ULIMIT confirmation

# /usr/local/psa/admin/sbin/websrv_ulimits --get
nginx:-1
apache:-1

It seems that the problem is that it is not set.

Solution procedure

# grep 'Max open files' /proc/$(cat /var/run/nginx.pid)/limits
Max open files            1024                 4096                 files

# ps axl | grep nginx:.master
1     0 15982     1  20   0  29248  1644 sigsus Ss   ?          0:00 nginx: master process /usr/sbin/nginx
0     0 23605 14785  20   0 112808   976 -      R+   pts/0      0:00 grep --color=auto nginx:.master

The corresponding process ID is 15982

# cat /proc/15982/limits
Limit                     Soft Limit           Hard Limit           Units
Max cpu time              unlimited            unlimited            seconds
Max file size             unlimited            unlimited            bytes
Max data size             unlimited            unlimited            bytes
Max stack size            8388608              unlimited            bytes
Max core file size        0                    unlimited            bytes
Max resident set          unlimited            unlimited            bytes
Max processes             7159                 7159                 processes
Max open files            1024                 4096                 files
Max locked memory         65536                65536                bytes
Max address space         unlimited            unlimited            bytes
Max file locks            unlimited            unlimited            locks
Max pending signals       7159                 7159                 signals
Max msgqueue size         819200               819200               bytes
Max nice priority         0                    0
Max realtime priority     0                    0
Max realtime timeout      unlimited            unlimited            us

to repair

# /usr/local/psa/admin/sbin/websrv_ulimits --set 4096 --no-restart

nginx restart
apache restart

Verification

# /usr/local/psa/admin/sbin/websrv_ulimits --get
nginx:4096
apache:4096

# grep 'Max open files' /proc/$(cat /var/run/nginx.pid)/limits
Max open files            4096                 4096                 files

# ps axl | grep nginx:.master
1     0 24911     1  20   0  29248  1644 sigsus Ss   ?          0:00 nginx: master process /usr/sbin/nginx
0     0 25766 14785  20   0 112808   980 -      R+   pts/0      0:00 grep --color=auto nginx:.master

# cat /proc/24911/limits
Limit                     Soft Limit           Hard Limit           Units
Max cpu time              unlimited            unlimited            seconds
Max file size             unlimited            unlimited            bytes
Max data size             unlimited            unlimited            bytes
Max stack size            8388608              unlimited            bytes
Max core file size        0                    unlimited            bytes
Max resident set          unlimited            unlimited            bytes
Max processes             7159                 7159                 processes
Max open files            4096                 4096                 files
Max locked memory         65536                65536                bytes
Max address space         unlimited            unlimited            bytes
Max file locks            unlimited            unlimited            locks
Max pending signals       7159                 7159                 signals
Max msgqueue size         819200               819200               bytes
Max nice priority         0                    0
Max realtime priority     0                    0
Max realtime timeout      unlimited            unlimited            us
#

Check in Plesk control panel

No problem detected