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-10

• iPXE: fog-ipxe v2.0.0-fog.9 (forum 18271, #1859). iPXE now reads EFI variables such as SecureBoot and SetupMode directly, and limits the walk through the firmware’s variable list. Before, firmware that never ends that list hung iPXE on an ${efi/...} setting. Run the update to install the new binaries.
• FOG Agent: an admin sets the directory-join cooldown, and a deploy clears it (#1863). After a domain join or rename attempt, the server waited a fixed hour before it sent the join credential again. The new setting FOG_AGENT_JOIN_COOLDOWN (FOG Configuration, FOG Agent) sets that wait in seconds, from 60 to 86400. The default stays 3600. A completed deploy task now clears a cooldown that is still running, so a reimaged host joins without the wait. This adds a schema update.
• “CSV (All)” export works on the host list (GH-1861, #1865). The button put the whole grid request on the URL. For the host list that URL was about 11 KB, and Apache refused it with “Request-URI Too Long”. The button now sends the request in a POST body.

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.