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-13

• Multicast: canceling one host no longer cancels the whole session (#1903, #1905, #1909). Before, a cancel on one host stopped udp-sender and canceled every host in the session. Now only that host leaves. When every remaining host has connected, the session starts at once, without the max-wait. The FOS receiver also gives up after the session’s max-wait when no sender answers. That half is in FOS EXP_20261019-150930, which the update installs.
• Secure Boot: the PXE menu enrollment is recorded (#1869, #1899). The Enroll Secure Boot Key menu item opened MokManager, and the host page still showed no enrollment. The server now records mok-pending when it serves the key. The host page tells you how to confirm it.
• Group create form: the dead boot fields are removed (#1901). Group Kernel, Group Kernel Arguments, Group Init and Group Primary Disk were saved and never used. To set these on many hosts, use Edit selected hosts on the Hosts list.
• Tab titles in non-ASCII languages (#1910). After sidebar navigation, a Japanese or Chinese tab title was garbled. It now matches a full page load.
• Japanese translation is complete (#1910, #1913). Every message is translated. Uptime no longer shows an English plural s after a translated unit, such as 日s.

Thank you to @mashiro-mikage for the tab title fix, the Japanese translation, and the uptime fix.

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.