Websites hosted on a Plesk server with Imunify360 are intermittently unavailable: Error establishing a database connection

Symptoms

• Imunify360 packages have been recently upgraded on a Plesk server to version 3.7.9 or 3.7.10:

  # grep imunify360 /var/log/yum.log
  Nov 14 03:17:08 Updated: imunify360-webshield-bundle-1.4-22.el7.x86_64
  Nov 14 03:17:19 Updated: imunify360-firewall-3.7.9-1.noarch
  Nov 14 03:17:21 Updated: imunify360-php-i360-0.6-4.el7.x86_64
  Nov 14 03:17:21 Updated: imunify360-firewall-plesk-3.7.9-1.noarch

• After these updates, websites that use the mysqli function became inaccessible with the following message in a web-browser:

  PLESK_INFO: Error establishing a database connection

  OR

  Webmail is not accessible with 500 error:

  PLESK_INFO: The server encountered an internal error or misconfiguration and was unable to complete your request.

• In case of websites, the following error message appears in the /var/www/vhosts/example.com/logs/error_log file:

  CONFIG_TEXT: [proxy_fcgi:error] [pid 1075518] [client 203.0.113.2:38688] AH01071: Got error 'PHP message: PHP Warning: mysqli_query(): Empty query in /var/www/vhosts/example.com/httpdocs/site/wp-includes/wp-db.php on line 763\nPHP message: PHP Warning: mysqli_query(): Empty query in /var/www/vhosts/example.com/httpdocs/site/wp-includes/wp-db.php on line 763\nPHP message: PHP Warning: mysqli_free_result(): Couldn't fetch mysqli_result in /var/www/vhosts/example.com/httpdocs/site/wp-includes/wp-db.php on line 1469\nPHP message: PHP Warning: mysqli_free_result(): Couldn't fetch mysqli_result in /var/www/vhosts/example.com/httpdocs/site/wp-includes/wp-db.php on line 1469\n'

  OR

  CONFIG_TEXT: [warn] [client 203.0.113.2] mod_fcgid: stderr: PHP Notice: Constant SOME_CONSTANT_NAME already defined in /var/www/vhosts/example.com/httpdocs/index.php on line 30

  The following error appears after several attempts to refresh the domain main page:

  CONFIG_TEXT: Coding error detected, it must be fixed by a programmer: count_records_sql() expects the first field to contain non-negative number from COUNT(), '' found instead.

• In case of webmail, the following error message appears in /var/log/messages:

  CONFIG_TEXT: ns14 kernel: php-cgi[22556]: segfault at 55fe00000002 ip 00007ff39e989ff1 sp 00007ffd8a5c62e8 error 4 in libc-2.17.so[7ff39e81b000+1c3000]

• Also, /var/log/httpd/error_log contains the below error:

  CONFIG_TEXT: [core:notice] [pid 98536] AH00052: child pid 76264 exit signal Segmentation fault (11)

  OR

  CONFIG_TEXT: [fcgid:warn] [pid 22389:tid 139623783184128] (104)Connection reset by peer: [client 203.0.113.2:54058] mod_fcgid: error reading data from FastCGI server, referer: http://webmail.example.com/?_task=mail&_refresh=1&_mbox=INBOX
  [core:error] [pid 22389:tid 139623783184128] [client 203.0.113.2:54058] End of script output before headers: index.php, referer: http://webmail.example.com/?_task=mail&_refresh=1&_mbox=INBOX
  [fcgid:error] [pid 22386:tid 139624196786304] mod_fcgid: process /var/www/cgi-bin/cgi_wrapper/cgi_wrapper(10328) exit(communication error), get signal 11, possible coredump generated

Cause

Updated Imunify360 packages break web-server operability.

Resolution

The issue has been fixed in Imunify360 version 3.7.11. Update the extension to the latest version:

1. Log into Plesk.

2. Open Extensions > Updates.

3. Select Imunify360 extension.

4. Click Update.

Note: If auto-update for extensions has been disabled previously, enable the setting back at Extensions > Updates > Auto-update.