In addition to numerous new and upgraded packages, this release has the following highlights: Support is planned until the end of October 2020, handing over to 20.09. Postgresql for NixOS service now defaults to v11. The graphical installer image starts the graphical session automatically. Before you'd be greeted by a tty and asked to enter systemctl start display-manager. It is now possible to disable the display-manager from running by selecting the Disable display-manager quirk in the boot menu. By default zfs pools will now be trimmed on a weekly basis. Trimming is only done on supported devices (i.e. NVME or SSDs) and should improve throughput and lifetime of these devices. It is controlled by the services.zfs.trim.enable varname. The zfs scrub service (services.zfs.autoScrub.enable) and the zfs autosnapshot service (services.zfs.autoSnapshot.enable) are now only enabled if zfs is set in config.boot.initrd.supportedFilesystems or config.boot.supportedFilesystems. These lists will automatically contain zfs as soon as any zfs mountpoint is configured in fileSystems. nixos-option has been rewritten in C++, speeding it up, improving correctness, and adding a --all option which prints all options and their values.

The following new services were added since the last release:

When upgrading from a previous release, please be aware of the following incompatible changes: GnuPG is now built without support for a graphical passphrase entry by default. Please enable the gpg-agent user service via the NixOS option programs.gnupg.agent.enable. Note that upstream recommends using gpg-agent and will spawn a gpg-agent on the first invocation of GnuPG anyway. The dynamicHosts option has been removed from the networkd module. Allowing (multiple) regular users to override host entries affecting the whole system opens up a huge attack vector. There seem to be very rare cases where this might be useful. Consider setting system-wide host entries using networking.hosts, provide them via the DNS server in your network, or use environment.etc to add a file into /etc/NetworkManager/dnsmasq.d reconfiguring hostsdir. The 99-main.network file was removed. Maching all network interfaces caused many breakages, see #18962 and #71106. We already don't support the global networking.useDHCP, networking.defaultGateway and networking.defaultGateway6 options if networking.useNetworkd is enabled, but direct users to configure the per-device networking.interfaces.<name>.… options. The SLIM Display Manager has been removed, as it has been unmaintained since 2013. Consider migrating to a different display manager such as LightDM (current default in NixOS), SDDM, GDM, or using the startx module which uses Xinitrc.

SD images are now compressed by default using bzip2. OpenSSH has been upgraded from 7.9 to 8.1, improving security and adding features but with potential incompatibilities. Consult the release announcement for more information.