Unable to upgrade Plesk: backup is created with insecure permissions

Symptoms

• Plesk upgrade fails with the following error:

  CONFIG_TEXT: Trying to backup MySQL database...
  ERROR while trying to backup MySQL database: '/custom/backups/folder/mysql.preupgrade.17.8.11-18.0.20.20191031-181915.dump.gz' is created with insecure permissions '777' (expected '600'),
  dumps directory '/custom/backups/folder' has world-readable permissions '777'.
  Try to fix permissions on '/custom/backups/folder' or/and fix mount options for '/custom/backups/folder'.
  (Or set environment variable PLESK_ALLOW_INSECURE_DUMPS=1)

• Plesk backups location was changed to directory mounted as NFS:

  # mount | grep "folder"
  //share.example.com/folder on /folder type cifs (rw,relatime,vers=3.0,cache=strict,username=user,domain=,uid=0,noforceuid,gid=0,noforcegid,addr=203.0.113.2,file_mode=0777,dir_mode=0777,soft,persistenthandles,nounix,serverino,mapposix,rsize=1048576,wsize=1048576,echo_interval=60,actimeo=1)

Cause

Plesk prevents backups from being created in insecure storage.

Resolution

Use the environment variable PLESK_ALLOW_INSECURE_DUMPS to skip permissions check during the upgrade. Upgrade in this way should be done via command line.

1. Connect to the server using SSH.

2. Setup environment variable:

   # export PLESK_ALLOW_INSECURE_DUMPS=1

3. Launch Plesk installer and follow the text UI:

   # plesk installer