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-17

• FOS checks the server’s TLS certificate (#1978, #1980). The boot menu sends FOS the server’s public-key pin as fogpin=. FOS refuses a server whose key does not match. With no pin, FOS checks the chain against its own CA bundle. If that check fails, FOS warns once and continues.
• New task type: Performance Test (#1982). It is an advanced task. FOS times disk reads, network reads and decompression on the client, names the slowest one, and changes nothing on the disk. The host’s Performance tab, under History Items, lists each result. This adds schema 444.
• Audit: work that no person did is recorded as (system), not fog (#1984). fog is also the default admin’s username, so a rejected API token or a host that FOS registered looked like the admin’s action. This applies to the Audit Log, to Created By on records saved with no signed-in user, and to quick-registration tasks. Rows written before the update keep fog. Task e-mail through ${user-name} does not change.
• FOG_KERNEL_RAMDISK_SIZE describes what the value now does (#1986). This adds schema 445. It changes the text only, not the value.

FOS (kernel and init), from the Latest FOS release

An RC install or update downloads the Latest FOS release. Latest is now EXP_20261027-181357:

• Kernel 6.18.59, the current 6.18 LTS release.
• FOS verifies TLS, which is the client half of #1978.
• The Performance Test task.
• x64 and x86 boot an initramfs, not an ext2 initrd (FOGProject/fos#75). The file names stay init.xz and init_32.xz, and the boot menu does not change. /tmp is now a real RAM disk with a size limit: FOG_KERNEL_RAMDISK_SIZE sets the size, kept between 64 MB and half of the client’s memory.
  • Warning: a customized init can no longer be loop-mounted. Add your files as an overlay cpio appended to init.xz instead: https://docs.fogproject.org/en/latest/kb/how-tos/customize-the-fos-init/ . A post-init script needs no rebuild at all: https://docs.fogproject.org/en/latest/kb/how-tos/post-init-scripts/
  • If a client fails to boot with this init, go to FOG Configuration > Initrd Update and install the init from EXP_20261027-155909, the last ext2 init. Then report it on FOGProject/fos#75.

API documentation: https://docs.fogproject.org/en/latest/1.6/kb/integrations/api

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.