Test it on a lab or non-production server first. The upgrade from 1.5 to 1.6 is one-way: it changes the database schema, and there is no down-migration.

Changed since RC-15

• Multicast: a named session is no longer canceled before hosts join (#1922, #1923, #1924). RC-15 canceled a named session about 10 seconds after it started, and the PXE menu then rejected the session name.
• Multicast: a host cancel no longer ends a session that expects machines by name (#1925, #1926). Unregistered machines that joined by name keep receiving. End the session with its own Cancel.
• Multicast: the PXE join closes when udp-sender starts sending (#1927, #1928). A late machine could join a session already in transfer and receive a partial image. This adds schema 442 (multicastSessions.msTransferStart).
• Installer: the ssh2 extension matches the PHP that php-fpm runs (#1929, #1931). On Linux Mint, snapin uploads failed with a 500 because php-ssh2 went onto a different PHP version. Linux Mint now uses the distro PHP, as Ubuntu does. Forum: https://forums.fogproject.org/topic/18289
• Services: each daemon child opens its own database connection (#1930, #1933, #1934). A restarted service child could fail with “Packets out of order” and read empty settings.
• Dashboard and reports: per-day charts use your time zone (#1935, #1936, #1937). The imaging history graph showed each day one day early west of UTC. The per-day charts on the Imaging, Snapin, Audit, Fleet, Hardware and Storage reports now count each run on its day in FOG’s display zone.

Before you upgrade

• Back up your database and /opt/fog/.fogsettings.
• Read the release notes: https://github.com/FOGProject/fogproject/blob/rc-1.6.0/docs/release/1.6.0-release-notes.md
• 1.6 removes Display Manager, Directory Cleaner, User Cleanup, Client Updater, Green FOG and the persistentgroups plugin. Their data is dropped. The site and accesscontrol plugins move into core.
• PHP 7.4 or later is required. Plugins built for 1.5 do not load.

Install or update (as root)

• A 1.6 beta or RC server: run bin/updatefog.sh --channel rc from your FOG checkout.
• A 1.5 server installed from git: update to the current 1.5 stable, then run bin/updatefog.sh --channel rc from the checkout.
• A new server, or a 1.5 server installed from a tarball:
  curl -fsSL https://raw.githubusercontent.com/FOGProject/fogproject/working-1.6/bin/bootstrap.sh | bash -s -- --channel rc

Report problems

Open an issue at https://github.com/FOGProject/fogproject/issues. Include your FOG version, your OS, and the installer log from bin/error_logs/. Report a security problem through “Report a vulnerability” on the same repository, not in a public issue.