Cannot publish site in Web Presence Builder standalone: Failed to copy site files because an error occurred during publishing

Symptoms

• The publishing fails with the following:
  

  PLESK_INFO: Failed to copy site files because an error occurred during publishing. Contact the server administrator for assistance.

  OR

  PLESK_INFO: Unexpected server behavior. For details, see the product's log files. Some errors were written to log.

• Following entries in /usr/local/sb/tmp/sitebuilder.log:
  

  CONFIG_TEXT: [ERR] /JsonApi/ Cannot copy file to '3cf8a3edc494a705ac04bf9299256615.php' via FTP (ftp_put(/usr/local/sb/tmp/ftp_publish_cache_VofrH5_dir/3cf8a3edc494a705ac04bf9299256615.php): failed to open stream: No such file or directory)
  ..
  [EMERG] /JsonApi/ Symfony\Component\Debug\Exception\ContextErrorException: Warning: ftp_put(): Disk full - please upload later

Cause

Insufficient amount of disk space.

Resolution

Connect to the server using SSH, free some disk space and publish website once more.