These release notes for Ubuntu 18.04.4 LTS (Bionic Beaver) provide an overview of the release and document the known issues with Ubuntu 18.04 LTS and its flavors. For details of the changes applied since 18.04, please see the 18.04.4 change summary. The release notes for 18.04, 18.04.1, 18.04.2, and 18.04.3 are available as well.
The 'main' archive of Ubuntu 18.04 LTS will be supported for 5 years until April 2023. Ubuntu 18.04 LTS will be supported for 5 years for Ubuntu Desktop, Ubuntu Server, and Ubuntu Core. Ubuntu Studio 18.04 will be supported for 9 months. All other flavors will be supported for 3 years.
Official flavor release notes
Find the links to release notes for official flavors here.
Get Ubuntu 18.04.4 LTS
Download Ubuntu 18.04.4 LTS
Images can be downloaded from a location near you.
You can download ISOs and flashable images from: http://releases.ubuntu.com/18.04.4/ (Ubuntu Desktop and Server)
http://cdimage.ubuntu.com/ubuntu/releases/18.04.4/release/ (Less Popular Ubuntu Images)
http://cloud-images.ubuntu.com/daily/server/bionic/current/ (Ubuntu Cloud Images)
http://cdimage.ubuntu.com/netboot/18.04.4/ (Ubuntu Netboot)
http://cdimage.ubuntu.com/lubuntu/releases/18.04.4/release/ (Lubuntu and Lubuntu Alternate)
http://cdimage.ubuntu.com/ubuntu-budgie/releases/18.04.4/release/ (Ubuntu Budgie)
http://cdimage.ubuntu.com/ubuntukylin/releases/18.04.4/release/ (Ubuntu Kylin)
https://ubuntu-mate.org/download/ (Ubuntu MATE)
Upgrading from Ubuntu 16.04 LTS or 17.10
To upgrade on a desktop system:
Open the "Software & Updates" Setting in System Settings.
- Select the 3rd Tab called "Updates".
- Set the "Notify me of a new Ubuntu version" drop down menu to "For long-term support versions" if you are using 16.04 LTS; set it to "For any new version" if you are using 17.10.
Press Alt+F2 and type update-manager -c into the command box.
- Update Manager should open up and tell you that Ubuntu 18.04 LTS is now available.
If not you can run /usr/lib/ubuntu-release-upgrader/check-new-release-gtk
- Click Upgrade and follow the on-screen instructions.
To upgrade on a server system:
Install update-manager-core if it is not already installed.
Make sure the Prompt line in /etc/update-manager/release-upgrades is set to 'normal' if you want non-LTS upgrades, or 'lts' if you only want LTS upgrades.
Launch the upgrade tool with the command sudo do-release-upgrade
- Follow the on-screen instructions.
Note that the server upgrade will use GNU screen and automatically re-attach in case of dropped connection problems.
There are no offline upgrade options for Ubuntu Desktop and Ubuntu Server. Please ensure you have network connectivity to one of the official mirrors or to a locally accessible mirror and follow the instructions above.
New features in 18.04
32-bit PowerPC Support Dropped
The powerpc port is not included in the 18.04 release. See announcement for details.
ppc64el support support continues as previously.
Ubuntu 18.04.4 ships with a v5.3 based Linux kernel updated from the v5.0 based kernel in 18.04.3. This enables the latest hardware and peripherals available from IBM, Intel, and others. The 18.04 kernel delivers new features inherited from upstream, including:
- New support for a number of new Intel and AMD graphics chipsets
- New default networking queue management algorithms to improve networking on slow and congested links
Preliminary support for WiFi 6 (802.11ax)
- BTRFS swap file support
- New block I/O latency controller
- Numerous security related improvements
We also see notable Ubuntu specific achievements with:
Further AppArmor and security module improvements
- shiftfs filesystem providing LXD performance improvements
As well as the usual myriad of bug fixes for supported platforms.
As of 18.04.4, OpenJDK 11 is the default in 18.04.
OpenJDK 8 has moved to universe and will remain available there for the life of 18.04, to provide migration time for packages, custom applications, or scripts that can't be build with OpenJDK 11. OpenJDK 8 will be updated in 18.04 until Ubuntu 16.04 LTS reaches EOL in April 2021.
The default OpenSSL has been upgraded from 1.1.0 to 1.1.1 LTS series bringing improved performance and ability to use TLSv1.3 in select packages. Co-installable 1.0.2n series OpenSSL remains to be available as well.
In Ubuntu 18.04 LTS, gcc is now set to default to compile applications as position independent executables (PIE) as well as with immediate binding, to make more effective use of Address Space Layout Randomization (ASLR). All packages in main have been rebuilt to take advantage of this, with a few exceptions.
bolt and thunderbolt-tools have been promoted to main to provide security controls for Thunderbolt devices.
Default CIFS/SMB protocol version change in CIFS mounts
Since 17.10, the default SMB protocol used when mounting remote CIFS filesystems via mount.cifs (from the cifs-utils package) changed to 2.1 or higher, depending on what is negotiated with the server. If no version is specified when mounting such a remote share, the following will be logged:
No dialect specified on mount. Default has changed to a more secure dialect, SMB2.1 or later (e.g. SMB3), from CIFS (SMB1). To use the less secure SMB1 dialect to access old servers which do not support SMB3 (or SMB2.1) specify vers=1.0 on mount.
Improved UEFI Secure Boot handling for the use of third-party modules
Ubuntu now allows you to generate a signing key when needed, as you install third-party (DKMS) modules. On install of a DKMS package, you will be prompted to enter a password that is used to enroll a signing key (an X509 certificate) that will then be used to sign the new kernel modules. The prompts will allow you to enter the same password twice, and describe the steps needed to enroll the new key at the next reboot. For more information, see https://wiki.ubuntu.com/UEFI/SecureBoot/DKMS.
New since 18.04.2
netplan.io has grown support for IPv6 Privacy Extensions, DHCP overrides, improved error reporting, support for WPA Enterprise wifi and 802.1x authentication, as well as support for IP tunnels.
netplan.io now will bring up network devices even if no IP address is specified for them, as long as they are configured in a file in /etc/netplan. This allows configuring "anonymous" bridges and integration with other networked services.
New since 17.10
Teaming support with libteam is available in NetworkManager.
New since 16.04 LTS
The default DNS resolver is systemd-resolved.
ifupdown has been deprecated in favor of netplan.io and is no longer present on new installs. The installer will generate a configuration file for netplan.io in the /etc/netplan directory. This netplan.io configuration in turn renders backend-specific configuration via either systemd-networkd or NetworkManager. Desktop users will see their system fully managed via NetworkManager as it has been the case in previous releases. Server users will now see their network devices managed via systemd-networkd. This only applies to new installations.
Given that ifupdown is no longer installed by default, the commands: ifup and ifdown are also unavailable. Please use the ip command to achieve similar functionality, specifically ip link set $device up and ip link set $device down.
The networkctl command is now available for users to see a summary of network devices. networkctl status will display the current global state of IP addresses on the system. networkctl status $device displays details specific to a network device.
The ifupdown package remains available and supported in Ubuntu main for users that find netplan does not currently meet their networking needs.
For more information about netplan.io, please refer to the manual page using the man 5 netplan command or visit https://netplan.io/.
Scripts in /etc/network/ifup.d and /etc/network/ifdown.d no longer work in this new configuration. For the systemd-networkd backend, similar scripts can be added into subdirectories of /usr/lib/networkd-dispatcher (dormant.d, no-carrier.d, off.d, routable.d), if networkd-dispatcher is installed. Later on, custom scripts can be placed in /etc/networkd-dispatcher and potentially also override the ones in /usr/lib.
Other base system changes since 16.04 LTS
The gpg binary is provided by gnupg2
For new installs, a swap file will be used by default instead of a swap partition.
Python 2 is no longer installed by default. Python 3 has been updated to 3.6. This is the last LTS release to include Python 2 in main.
The installer no longer offers the encrypted home option using ecryptfs-utils. It is recommended to use full-disk encryption instead for this release. (1756840)
OpenSSH now refuses to use RSA keys smaller than 1024 bits. ssh-keygen -l -f /path/to/key.pub can report the length of a key.
Updates and fixes in 18.04.2
Fixed a bug which prevented the login screen from appearing on early generation Intel GPUs (Core2 and Atom etc) (1727356)
Fixed memory leak in Nautilus (1798426)
Fixed OSK bug preventing uppercase letters being entered (1730211)
Fixed bug where two instances of an application were launched if you touched on the dock (1745888)
- Updated Firefox to version 65
Updated LibreOffice to 6.0.7
- Updated Thunderbird to 60.4.0
Fixed a bug which caused the dock to show on the lock screen (1769383)
Fixed a bug with Livepatch notifications startup ordering causing missing notifications (1809505)
New since 17.10
X is the default display server. Wayland is provided as a Technical Preview and is expected to be the default display server in 20.04 LTS. To try it out, just choose Ubuntu on Wayland from the cog on the log in screen. X.org logs may now be found at ~/.local/share/xorg
The installer offers a minimal install option for a basic desktop environment with a web browser and core system utilities. Many official 18.04 desktop flavors are using this new feature too!
Apps provided by GNOME have been updated to 3.28. For more details about GNOME 3.28, see their Release Notes.
LibreOffice has been updated to 6.0.
Emoji now show in color in most apps. Keyboard shortcuts for the emoji input chooser are Ctrl+. or Ctrl+;
Calendar now supports weather forecasts.
Some utilities have been switched to the snap format for new installs (Calculator, Characters, Logs, and System Monitor). Snap apps provide better isolation which allows them to be upgraded to new stable releases during the LTS lifecycle.
The Characters app replaces the older Character Map by default.
The Ubuntu Software app allows easy switching between different channels for Snap apps.
The To Do app has been added to the default normal install.
spice-vdagent is pre-installed for better performance for Spice clients such as the GNOME Boxes app.
The right-click method for touchpads without physical buttons has changed to a two-finger click instead of clicking in the bottom right of the touchpad. You can use the GNOME Tweaks app (not installed by default) to change this setting.
Although libinput is the default driver for mice and touchpads, it is now possible to use the synaptics driver with the Settings app. Support for the synaptics driver will be dropped in a future Ubuntu release.
Computers will automatically suspend after 20 minutes of inactivity while on battery power.
GNOME Shell now supports Thunderbolt 3.
Other highlights since 16.04 LTS
32-bit installer images are no longer provided for Ubuntu Desktop.
The Ubuntu Desktop now uses GNOME instead of Unity.
GDM has replaced LightDM as the default display manager. The login screen now uses virtual terminal 1 instead of virtual terminal 7.
Window control buttons are back on the right.
Driverless printing support is now available.
GNOME's built-in screen keyboard is used instead of Onboard.
Calendar has a Week View and supports recurring events.
- These apps have received major user interface redesigns: Disk Usage Analyzer, Files (nautilus), Remmina, Settings, and Ubuntu Software.
System Log has been replaced by Logs, an app to view logs from the systemd journal.
Many GNOME apps now have a Keyboard Shortcuts popup available in the app menu.
gconf is no longer installed by default since it has long been superseded by gsettings. Note that statistics and preferences for the Aisleriot card games will be reset when upgrading from 16.04 LTS or 16.10. gconf will be removed from the Ubuntu package archives in a future Ubuntu release.
The Ubuntu GNOME flavor has been discontinued. If you are using Ubuntu GNOME, you will be upgraded to Ubuntu. Choose the Ubuntu session from the cog on the login screen if you would like the default Ubuntu experience.
Install gnome-session then restart your computer and choose GNOME (or GNOME on Wayland) from the cog on the login screen if you would like to try a more upstream version of GNOME. If you'd like to also install more core apps, install the vanilla-gnome-desktop metapackage.
Updates and fixes in 18.04.2
Only "main" component enabled after install (1783129)
/etc/default/grub.d/50-curtin-settings.cfg overwrites GRUB_CMDLINE_LINUX_DEFAULT (1527664)
Install failed on disk previously used for ZFS (1782744)
New since 17.10
The next generation Subiquity server installer, brings the comfortable live session and speedy install of Ubuntu Desktop to server users at last.
N.B., If you require multipath you will want to continue to use the alternate installer which can be downloaded from http://cdimage.ubuntu.com/releases/18.04/release/
A new feature in the server installer in 18.04.3 is that it automatically checks for a new version of the installer snap on startup and offers to update to a new version if it is available.
Also new in 18.04.3 is support for encrypted LVM volume groups and reusing existing partitions, as well as LVM, RAID, vlans, and bonds which were added in 18.04.1.
There are some known limitations in the reuse of existing partitions:
Reusing a partition that was part of an LVM volume group or RAID can fail. This can be worked around by switching to another tty and destroying the RAID or VG by hand, then restarting. If there is no other data on the same drive that you want to keep, reformatting the drive entirely also works.
The installer cannot add or remove individual partitions. You can format (or not) and mount existing partition, but not add a partition to free space or remove a single partition from a drive.
We hope to fix both of these limitations via snap updates well before the next point release.
Please see the Network configuration section of these release notes.
LXD is the system container manager that ships with all Ubuntu servers.
Ubuntu 18.04 includes the all new LXD 3.0 release, some of the highlights include:
- Clustering of LXD servers (one big virtual LXD)
- Support for NVIDIA runtime passthrough
- Remote transfer of custom storage volumes
- Extended /dev/lxd API inside the containers
- Support for port redirection
- Numerous improvements to the command line tools
To learn more about LXD 3.0, read the release announcement.
A new external tool called lxd-p2c is also available to turn existing systems into LXD containers.
QEMU has been updated to the 2.11.1 release.
See the Changelog for major changes since Artful.
Among many other changes, fixes around Meltdown/Spectre are included. Since fully utilizing these mitigations needs more than just an upgrade, it is recommended to read details at the qemu.org blog post.
QEMU in Ubuntu 18.04 now has rdma support enabled as over the past year much unification in the rdma-core project has occured.
Migrations from former versions are supported just as usual. When upgrading it is always recommended to upgrade the machine types allowing guests to fully benefit from all the improvements and fixes of the most recent version.
The packaging now builds libvirt storage drivers as pluggable libraries. This slims down the installation requirements but some drivers of less general interest will now be found in universe. (ex: gluster, sheepdog, zfs). On the other hand that means that a few formerly integrated features like rbd or zfs now might require you to install the package after upgrade e.g. in this case libvirt-daemon-driver-storage-zfs.
Ubuntu includes 17.11.x the latest stable release branch of DPDK.
See the Release Notes for details.
By the new Stable Release exception for DPDK future stable updates to 17.11.x will be made available to Ubuntu 18.04
Open vSwitch 2.9
Open vSwitch has been updated to 2.9.
Please read the release notes for more detail.
In Ubuntu 18.04 chrony will replace ntpd as the recommended server for the NTP protocol. See the upstream changelog for an overview of recent changes as well as the FAQ which will help for smooth conversions from NTP.
The comparison among ntp servers by the chrony maintainers may interest some users looking to see a high level reason why this change was made. It does lack the rather new and not yet completely ready ntpsec, but otherwise is a fair analysis.
For simple time sync needs the base system already comes with systemd-timesyncd. Chrony is only needed to act as a time server or if you want the advertised more accurate and efficient syncing.
Going along with this change, ntpd has been demoted from main to universe. ntpd will continue to work but will only receive best-effort security maintenance. When upgrading to Ubuntu 18.04 it is highly recommended to migrate to chrony if you had set up ntpd before.
The version was updated to 18.2. Notable new features include:
- VMware: support for 64-bit platforms and identifying OVF datasource provided
- GCE: Improvements and changes to ssh key behavior for default user.
- Azure pre-provisioning speed improvements
- NoCloudKVM and EC2 tests now run in continuous integration.
OpenNebula: Improve network configuration support.
- New cloud-init command-line tools available: status, analyze and clean
- New ubuntu cloud-config modules for managing snaps and ubuntu-advantage services
The version was updated to 18.1. Notable features include:
- Add experimental zpool and zfs filesystem support, including ZFS on root.
Add support for installing remote sources that are a filesystem image. (1746348)
- Add pollinate user-agent configuration support.
Default config now automatically tars curtin logs upon error using new curtin collect-logs command.
storage: accept filesystem mount options (1709284)
- Extensive integration test coverage and improvements.
The version was updated to 2.4b2. Notable features include:
- Add audit logging
- Add KVM pod support to create tags, select the storage pool, and compose machines with multiple storage pools.
- Add UI for DNS management
- Add the commissioning template framework for HBA management.
- Add the commissioning template framework for Firmware Upgrades.
- Improve UI performance by performance.
- Improve MAAS' backend performance and
- Improve the UI for the Settings.
- Add experimental support to configure zfs as the root filesystem.
- Switch to use Chrony instead of ntp.
SSSD was updated to version 1.16.x and its secrets service is now enabled. Previously it was disabled because it required the http-parser library which lived in Universe, but a successful MIR brought it to main so SSSD could link with it.
The defaults for autofs related configuration settings changed in SSSD 1.14.0 (see https://pagure.io/SSSD/sssd/issue/2858). If you are upgrading from SSSD 1.13 in Xenial, you might have to explicitly specify all ldap_autofs_* settings in your sssd.conf to match your data in LDAP.
These are the defaults, based on the setting of ldap_schema:
nisMap (rfc2307, autofs_provider=ad), otherwise automountMap
ou (rfc2307), automountMapName (rfc2307bis, ipa, ad)
nisMapName (rfc2307, autofs_provider=ad), otherwise automountMapName
nisObject (rfc2307, autofs_provider=ad), otherwise automount
cn (rfc2307), automountKey (rfc2307bis, ipa, ad)
cn (rfc2307, autofs_provider=ad), otherwise automountKey
nisMapEntry (rfc2307, autofs_provider=ad), otherwise automountInformation
See bug #1767886 for details.
The vfs module aio_linux was removed from the samba-vfs-modules package (see Debian bug #881239), and it's nowadays also no longer present in upstream Samba code. The upstream Samba bug #13128 has more details.
If you had a configuration that included this module in a share, something like this:
[someshare] ... vfs objects = aio_linux
Then when this share is accessed, the server will notice it can't find the aio_linux module and fail. You should remove the aio_linux from the list of vfs objects that are being loaded.
Note that testparm(1) won't catch this type of error (see bug #1778860).
PHP was updated to version 7.2.x. For upstream guidance on migrating from PHP 7.1 (Artful's version) to 7.2: http://php.net/manual/en/migration72.php. Also of relevance might be the 7.0 to 7.1 migration documentation: http://php.net/manual/en/migration71.php.
Apache was updated to version 2.4.29. Additionally, HTTP/2 support is now enabled in 18.04.
landscape-client has been ported to Python 3 and is now available to install on the default image.
- New dynamic MOTD support for Canonical Livepatch. This indicates, at a glance, the status of livepatches when logging in on a console.
New enable-fips-updates command to enable a special FIPS repository with non-certified updates for FIPS enabled systems.
s390x-specific enhancements (since 17.10)
s390-tools major version upgrade to v2.3.0 (1735447)
cryptsetup rebase and enhancements in support of dm-crypt (1724592)
protected key support for dm-crypt (1741904)
Improved memory handling (1734120)
support for new crypto hardware CEX6S (1735437)
AP bus kernel API for KVM (1732449)
parted update for fdasd/vtoc (1737144)
openssl-ibmca rebase (1747626)
opencryptoki rebase for EP11 and ECC enhancement (1751272)
lock optimization enhancement (1747877)
auto detect layer2 setting in qeth driver (1747639)
Kernel support for STHYI/LPAR (1736093)
rebase libpfm4 for z13/z13s CPU-MF hardware counters (1741905)
Ubuntu 18.04 includes the latest OpenStack release, Queens, including the following components:
OpenStack Identity - Keystone
OpenStack Imaging - Glance
OpenStack Block Storage - Cinder
OpenStack Compute - Nova
OpenStack Networking - Neutron
OpenStack Telemetry - Ceilometer, Aodh, Gnocchi, and Panko
OpenStack Orchestration - Heat
OpenStack Dashboard - Horizon
OpenStack Object Storage - Swift
OpenStack Database as a Service - Trove
OpenStack DNS - Designate
OpenStack Bare-metal - Ironic
OpenStack Filesystem - Manila
OpenStack Key Manager - Barbican
Please refer to the OpenStack Queens release notes for full details of this release of OpenStack.
OpenStack Queens is also provided via the Ubuntu Cloud Archive for OpenStack Queens for Ubuntu 16.04 LTS users.
WARNING: Upgrading an OpenStack deployment is a non-trivial process and care should be taken to plan and test upgrade procedures which will be specific to each OpenStack deployment.
Make sure you read the OpenStack Charm Release Notes for more information about how to deploy Ubuntu OpenStack using Juju.
ARM64 performance considerations
Ubuntu supports 4k page size, 64K page size has benefits to certain applications and benchmarks. Please follow this link for ARM64 performance considerations that may yield similar results with 4k page size.
As is to be expected, with any release, there are some significant known bugs that users may run into with this release of Ubuntu 18.04. The ones we know about at this point (and some of the workarounds), are documented here so you don't need to spend time reporting these bugs again:
- The default I/O scheduler has changed. SCSI multi-queue is now enabled for appropriate devices. This changes the set of available I/O schedulers for that device to be only those schedulers which are multi-queue aware; currently only mq-deadline and none. Testing has shown this to be advantageous in the common case. This does however mean that manually selected schedulers may not be available leaving a unexpected scheduler enabled. This affects both the kernel command line elevator= option and any udev rules for specific devices.
The computer suspends after 20 minutes of inactivity on battery power even if a user is logged in remotely. (GNOME:gnome-control-center#22)
- Bluetooth audio devices cannot be used in the Greeter. This will cause issues for people using the accessibility features such as screenreaders at the login screen. Once logged in everything should work as expected.
Some admin utilities will not work with GNOME on Wayland since the apps have not been adapted to use PolicyKit to only use admin privileges for the specific functions needed. Also, some screenshot and screencast apps and all remote desktop server apps do not currently work on GNOME on Wayland. As a workaround, you can use the default Ubuntu session.
Exiting the live session may get stuck with a "A start job is running for " error. You may need to forcefully power off the computer if you see this. (1706939)
The Dock and Appindicator system extensions appear to be Off in tools like GNOME Tweaks. (They are on but cannot be disabled because they are system extensions for the Ubuntu session.) (1718850)
Tracker is not installed by default. When installed, you must log out and log back in for the tracker service to start (1697769)
When an external monitor is connected to a laptop, the login screen is only displayed on the internal one and in some case is not visible (1723025)
The warning dialog when a user force a UEFI installation does not respond to input event and the installation is then blocked at this stage (1724482) Avoid yourself some troubles and do not force a UEFI installation without a UEFI partition, grub-installer will fail anyway.
Doing an "Entire disk" installation over an existing LVM installation will fail because the installer selects the wrong boot device (1724417) Use custom partitioning instead and manually select the right boot device in the combo box.
The Files app remains at 3.26.
Upgrading via the installer (Ubiquity) is deemed not safe due to bugs in apt-clone and so is no longer supported. (1756862) UIFE - remove ubiquity upgrade option.
Setting a ulimit may cause segfaults in certain applications, especially those using webkit2gtk. Disabling the ulimit should restore normal functionality. More information in this Debian news entry: https://salsa.debian.org/webkit-team/webkit/blob/wk2/unstable/debian/NEWS
The installer can crash, especially noticeable on HiDPI screens where scaling has been applied (1751252). The workaround is to boot into the live session, change Settings > Devices > Displays > Scale = 100%, click Apply and proceed with installation by clicking "Install Ubuntu 18.04 LTS".
The installer may not use the EFI partition you expect it to use (1396379). If you've experienced this, this bug comment has advice to repair the situation: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1396379/comments/8
LVM Entire Disk option does not use entire disk (1785321)
Partitioning step allows to configure LVM across multiple devices without requiring to setup a separate /boot partition. This may lead to failure to install the bootloader at the end of the installation, and failures to boot the resultant installations. (1680101)
LVM configuration cannot be removed when volume groups with the same name are found during installation. Partitioner does not support installation when multiple conflicting/identical volume groups have been detected. For example reinstalling Ubuntu with LVM across multiple disk drives that had individual LVM installations of Ubuntu. As a workaround, please format disk drives prior to installation, or from the built in shell provided in the installer. (1679184)
cio_ignore blacklist is no longer active after installation, because not all install-time parameters, like cio_ignore (s390x), are propagated to the installed system. Workaround is to edit /etc/zipl.conf to apply these and re-run sudo zipl to update the IPL. (1571561)
As of 18.04.4, the Raspberry Pi 4B is supported. For users upgrading to the release, please ensure all packages including the kernel are up to date on a prior supported model (e.g. 3B, 3B+) before attempting to boot the card on a 4B. If you encounter problems, verify (by booting on the older model) that you are running kernel version 5.3 or above (with uname -r), and that no updates are pending.
The WiFi firmware present for the BCM4345/6 chipset (found on the Raspberry Pi 3A+, 3B+, and 4B) in the 18.04.4 release is out of date and results in unreliable operation when used with 5Ghz 802.11ac WiFi. Note that most 5Ghz WiFi routers at present are 802.11n or a combination of 802.11n and 802.11ac, so the expected impact is low. However, the firmware package is in the process of being updated to fix this and will be updated in 18.04 as a priority after the release of 18.04.4. (1862760)
For Ubuntu Core 18 on the Raspberry Pi, the vc4-fkms-v3d overlay is included in the default boot configuration. This is known to cause issues on the Raspberry Pi 3A+ on which the overlay allocates half the available memory, leaving insufficient memory for the system to operate correctly (1848247). The recommended workaround is to comment out the dtoverlay line in config.txt on the system-boot partition (the first partition on the card), like so:
The Pimoroni Fan Shim for the Raspberry Pi 4 re-uses the serial console pins, pins 8 and 10 (GPIO14 and GPIO15 respectively), on the GPIO header to control its RGB LED. This results in "noise" on the serial line which stops u-boot during startup (as it thinks a key has been pressed). Adding the following line to config.txt on the system-boot partition (the first partition on the card) disables the serial console permitting the boot sequence to complete:
The release notes for the official flavors can be found at the following links:
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