It is not possible to log into phpMyAdmin: failed to read session data: files (path: @@PMA_TEMP_DIR@@/session)

Symptoms

• Plesk 17.8 is used:

  # plesk version
  Product version: Plesk Onyx 17.8.11 Update #56
  Update date: 2019/06/22 01:48
  Build date: 2019/06/05 13:43
  OS version: CentOS 7.6.1810
  Revision: 388af031cc753ceca2cd81d6db5847338429dd4b
  Architecture: 64-bit
  Wrapper version: 1.2

• Plesk was created via cloning

  NOTE: To confirm that server has been cloned, you can check presence of log like /var/log/plesk/install/plesk_17.8.11_reset_instance_data.log. Since this log could be rotated/removed, absence of it does not mean that the instance is not cloned. 

• The following error message occurs on an attempt to open phpMyAdmin in Domains > example.com > Databases or in Tools & Settings > Database Servers > next to the MySQL server name:

  CONFIG_TEXT: Error during session start; please check your PHP and/or webserver log file and configure your PHP installation properly. Also ensure that cookies are enabled in your browser.
  
  session_start(): open(SESSION_FILE, O_RDWR) failed: No such file or directory (2)
  session_start(): Failed to read session data: files (path: ./tmp/session)

  OR

  CONFIG_TEXT: Failed to store CSRF token in session! Probably sessions are not working properly.

• The following entry is found in /var/log/syslog/:

  CONFIG_TEXT: GenerationTree mysql[1457]: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

• SessionSavePath is set to ./tmp/session:

  Debian, Ubuntu:

  # grep -rin 'SessionSavePath' /opt/psa/admin/htdocs/domains/databases/phpMyAdmin/libraries/config.default.php
  714: * @global integer $cfg['SessionSavePath']
  716:$cfg['SessionSavePath'] = '@@PMA_TEMP_DIR@@/session';

  CentOS:

  # grep -rin 'SessionSavePath' /usr/local/psa/admin/htdocs/domains/databases/phpMyAdmin/libraries/config.default.php
  714: * @global integer $cfg['SessionSavePath']
  716:$cfg['SessionSavePath'] = '@@PMA_TEMP_DIR@@/session';

• phpMyAdmin package is not configured:

  # dpkg -l | grep -i phpmyadmin
  iU psa-phpmyadmin 4.8.3-ubuntu16.04.build1708180919.15 all MySQL web administration tool adapted for Plesk Onyx

Cause

Issue is caused by bug with ID #PPPM-9529, which is planned to be fixed in product future updates.

Resolution

As workaround, until fix available: