Apache failed to start: (24)Too many open files: Init: Can’t open server certificate file

Dmitry Bystrov

10 months ago

Symptoms

It is not possible to start or restart Apache web server, all websites are down:

# service httpd start
Starting httpd: [FAILED]

Or:

# systemctl start apache2.service
Job for apache2.service failed because the control process exited with error code. See "systemctl status apache2.service" and "journalctl -xe" for details.
The following error can be found in the /var/log/httpd/error_log file ( /var/log/apache2/error.log in Debian and Ubuntu):

[error] (24)Too many open files: Init: Can't open server certificate file /usr/local/psa/var/certificates/cert8bV9dbI
'import site' failed; use -v for traceback

Or:

AH00015: Unable to open logs
The following error is shown when trying to start Apache using the strace utility (in Debian and Ubuntu, Apache binary is /usr/sbin/apache2 ):

# strace -q -vttT -s4096 /usr/sbin/httpd -e debug -k start
...
open("/var/www/vhosts/system/example.com/logs/access_ssl_log", O_WRONLY|O_CREAT|O_APPEND|O_CLOEXEC, 0666) = -1 EMFILE (Too many open files) <0.000011>
write(408, "[Wed Sep 13 21:27:55.156566 2017] [log_config:error] [pid 22172:tid 140081010858112] (24)Too many open files: AH00649: could not open transfer log file /var/www/vhosts/system/example.com/logs/access_ssl_log.n", 235) = 235 <0.000034>
write(2, "AH00015: Unable to open logsn", 29) = 29 <0.000022>

Cause

The maximum allowed number of file descriptors is not enough for Apache web server.

Resolution

Click on a section to expand

For Systemd OS (RHEL 7-based, Debian 8, Ubuntu 16.04)

Connect to the server via SSH
Set desired open files limit to for both Apache and Nginx, using the following shell utility
# /usr/local/psa/admin/sbin/websrv_ulimits --set 32768 --no-restart
Restart Apache and nginx services at Plesk > Tools & Settings > Services Management to apply changes.

Another solution is to increase open file limit manually:

Create the directory /lib/systemd/system/httpd.service.d/ directory ( apache2.service.d in Debian and Ubuntu):

# mkdir /lib/systemd/system/httpd.service.d/
In this directory, create limit_nofile.conf file in it with the following content:

# cat /lib/systemd/system/httpd.service.d/limit_nofile.conf
[Service]
LimitNOFILE=65536
Reload systemd unit files and start Apache (in Debian and Ubuntu, service is called apache2.service ):

# systemctl daemon-reload
# systemctl start httpd.service

Note: If the issue still persists on the Debian-like systems, increase limits through APACHE_ULIMIT_MAX_FILES environment variable as it is described below for SysVinit OSes.

For SysVinit OS (RHEL 6-based, RHEL 5, Debian 7)

For Debian and Ubuntu:
1. Connect to the server via SSH
2. Put the APACHE_ULIMIT_MAX_FILES='ulimit -n 131072' line into the /etc/apache2/envvars file:
  
  # grep ULIMIT /etc/apache2/envvars
  APACHE_ULIMIT_MAX_FILES='ulimit -n 131072'
3. Restart the Apache service:
  
  # service apache2 restart
For RHEL-based operating systems:
1. Connect to the server via SSH
2. Comment the following section in the /usr/sbin/apachectl file:
  
  #ULIMIT_MAX_FILES="ulimit -S -n `ulimit -H -n`"
  #-------------------- --------------------
  #|||||||||||||||||||| END CONFIGURATION SECTION ||||||||||||||||||||
  #Set the maximum number of file descriptors allowed per child process.
  #if [ "x$ULIMIT_MAX_FILES" != "x" ] ; then
  #$ULIMIT…

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