Unable to upgrade Plesk: backup is created with insecure permissions

Symptoms

• Plesk upgrade fails with the following error:

  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. Set up the necessary environment variable by executing the following command:

   # export PLESK_ALLOW_INSECURE_DUMPS=1

3. Launch the Plesk installer and follow the text instructions by executing the following command:

   # plesk installer