Please don’t post to say everything was great on my side or yes, I have the same error but leave the space for people having issues, or even better: for people having solutions!
Use 
instead to let us know you’re suffering from the same so we can respond to the highest impacted issues first! 
New issues:
Python packages from PIP and AUR - how to upgrade them - detailed instructions
Read this post .
NVIDIA 495xx driver is spamming invalid dbus messages resulting in Gigabytes of log files
Depending on the usage of the GPU, the driver spams invalid dbus messages at a very high rate (~100 lines per second) which will fill multiple Gigabytes of system log files within a few days.
Upstream NVIDIA Bug: [BUG] NVIDIA v495.29.05 driver spamming dbus-enabled applications with invalid messages - Linux - NVIDIA Developer Forums
Temporary Fix: Install nvidia-fake-powerd (AUR) - (don’t forget to start / enable the service with sudo systemctl enable nvidia-fake-powerd and sudo systemctl start nvidia-fake-powerd)
nvidia-fake-powerd is a service, which will redirect those dbus messages to /dev/null, so technically it just prevents that it’s written into system log files.
No search results in application launcher when using multiple kickoff instances
Edit: Bug is now fixed Upstream. It will be in the next Plasma 5.23.5 Release, which is scheduled at Tue 2022-01-04.
Solution 1: Manually Downgrading the Kickoff Applet until the Bug is fixed Upstream.
Solution 2: Only have one Kickoff Applet, by removing the other ones.
Upstream KDE Bug: 443131 – When there’s more than one Kickoff, clicking on the old one causes search to be broken until you search with the new one
(Basically they completly rewrote the codebase of the kickoff applet, which seems to only create a single search instance, which they try to bind to multiple kickoff applets. However this seems to result in some NULL exceptions, as it fails to force focus on the search object.)
Workaround Tutorial: No search results in application launcher - #6 by alkl
Xorg crashes with multiple monitors if portrait view or custom display scale is used on 2nd display (possibly leading to infinite login loop)
See
Error: LightDM infinite login loop
or
[Stable Update] 2021-11-19 - Kernels, Gnome 41.1, Plasma 5.23.3, Frameworks 5.88, LxQt 1.0, Xorg-Server 21.1, Mesa - #244 by LS650V
for problem descriptions and possible solutions.
KDE Plasma shows visual graphical errors
This is a known issue based on changes within SVG files . Clearing the Plasma SVG cache fixes it. Do this: rm ~/.cache/*plasma* ; killall plasmashell && kstart5 plasmashell
If did not help, try strengthened variant of clearing cache (to be sure that it is not the cache-related issue)
- Log out from user session to shutdown all KDE and user apps which could use the cache.
- Enter TTY, for example TTY3: Ctrl+Alt+F3.
- Login in that textual terminal.
- Clear all cache and extra KDE-related stuff by entering these 3 commands: KDE - ArchWiki .
- Type
systemctl reboot to reboot PC.
This update removes linux512. What you can do.
Time to time we have to drop kernel series from our repos. So either you adopt to the new 5.15 LTS or choose any other still supported kernel we have. Note: 5.13 is marked EOL and will be dropped next!
sudo mhwd-kernel -r linux512
sudo pacman -Syu
sudo mhwd-kernel -i linux515
Nvidia 495xx driver series drops Kepler support; need to manually switch to 470xx.
mhwd’s video-nvidia now provides 495xx; if you need 470xx you must manually switch before updating, by using the commands below.
With the new 495xx driver series a lot of Wayland adjustments got added. Also Nvidia decided to remove Kepler support . Therefore you may want to switch drivers to 470xx series, which still supports those graphic cards:
sudo mhwd -r pci video-nvidia
sudo mhwd -i pci video-nvidia-470xx
Nvidia 340xx driver series no longer works.
This driver is end of life by NVIDIA, you should not be using it as there are serious security issues with this driver. You have to either get newer supported hardware or switch to Nouveau:
#remove old
sudo mhwd -r pci video-nvidia-340xx
sudo mhwd -r pci video-linux
#install new nouveau
sudo mhwd -i pci video-linux
Reboot after and you're done.
Pamac can’t handle file conflicts checking
If you experience this issue update libpamac with: sudo pacman -Sy libpamac
For details see: Hangs on file conflicts checking (#1138) · Issues · Applications / pamac · GitLab
Shortcut Scrolling doesn’t work any more in Cinnamon
You now need to hold down the ⊞ (aka “the Windows key”) to make the mouse wheel scroll the timeline forwards & backwards. Source
Fullscreen loses focus
Symptoms:
Full-screen apps like YouTube and games:
- Load fine but after briefly showing the application you’re dumped back into your Desktop Environment (DE) whilst the application was still running fine in the background.
- Clicking on the running application briefly brings you back to it but you’re dumped again to the DE after a second or 2.
Solution:
disable the Desktop Icons (DING) extensions
SDDM shows wrong/default theme
Solution:
Set SDDM theme to Breath in System Settings / Startup and Shutdown / Login Screen (SDDM).
Older Issues:
With 21.1.4 and initial 21.1.5 release it was not possible to install on non-BTRFS filesystems
Seems grub-btrfs preinstalled in version 4.10.1 introduced a regression to error out when no BTRFS filesystem was found on your system. This was part of 21.1.4 ISO and our initial 21.1.5 release. Please re-download 21.1.5, which is now fixed.
Fixed ISOs:
----------------
58de4cd58b23fea2ef69c055dd0088726350294a manjaro-gnome-21.1.5-211008-linux513.iso
a8af15b768479ea321c897aa83e573e26bd61784 manjaro-gnome-21.1.5-minimal-211008-linux513.iso
aef8a60820666cddce79c980258693d0cf13da9a manjaro-gnome-21.1.5-minimal-211008-linux54.iso
564c64ddf342c9b7483c469a6d8dca2f94492719 manjaro-kde-21.1.5-211008-linux513.iso
3781a3c0d3a92496b1418dafb49cef247379aa93 manjaro-kde-21.1.5-minimal-211008-linux513.iso
1f4c83be758275e3d0bb17a0b32138b7a0b313a8 manjaro-kde-21.1.5-minimal-211008-linux54.iso
00737362c81c3c3d4ec7fba6f7a7ec72701a0450 manjaro-xfce-21.1.5-211008-linux513.iso
c2e2f5018d9a50a1112bbcc761a22c8e4dcb7275 manjaro-xfce-21.1.5-minimal-211008-linux513.iso
a34e27a17ab5fcc6473f1ad503d2049a9c904608 manjaro-xfce-21.1.5-minimal-211008-linux54.iso
Broken ISOs:
----------------
91cf900bb978dfbb3d32fec083c27d4c428b03ca manjaro-gnome-21.1.5-211008-linux513.iso
c9f07d7ab4f3bb3a75b1a3c84e909cbf3bd74309 manjaro-gnome-21.1.5-minimal-211008-linux513.iso
7e0673c604e1ce267f59d0056ddf819cede21f38 manjaro-gnome-21.1.5-minimal-211008-linux54.iso
1f56c7feaf7c5fea485b30a6d3c513fb3d0188bb manjaro-kde-21.1.5-211008-linux513.iso
0922345bdec24b2eb5ed6f635c600b2a499a1ed9 manjaro-kde-21.1.5-minimal-211008-linux513.iso
74fd38b172be9c996d6d59e40e4a730b93f9c88f manjaro-kde-21.1.5-minimal-211008-linux54.iso
3b9409492b791f4380f617489c63e327ae7f6d53 manjaro-xfce-21.1.5-211008-linux513.iso
10a8d165d9bd0a8edcae1a640e0c753b1ff1c54c manjaro-xfce-21.1.5-minimal-211008-linux513.iso
3d72ecdb9494f0e7876018286f875f1a0cef1191 manjaro-xfce-21.1.5-minimal-211008-linux54.iso
3d72ecdb9494f0e7876018286f875f1a0cef1191 manjaro-xfce-21.1.5-minimal-211008-linux54.iso
Steam shows black screen
Opting in or out for Steam beta changes nothing.
Workaround:
LD_PRELOAD=/lib/libharfbuzz.so steam
Buzzing sound while using headphones.
Workaround:
sudo nano --backup /etc/tlp.conf
- set
SOUND_POWER_SAVE_ON_AC=0
- Only if you have to, set
SOUND_POWER_SAVE_ON_BAT=0 as well
No idea how much it affects battery life, though.
Vertex-Maia-Icons are messed up.
Workaround:
- Vertex-Maia-Icons will be dropped from the repository soon:
- Choose some new icon theme.
Unable to login in remotely using ssh using rsa keys
After this upgrade authentication might not work and might find the following error in the ssh log:
userauth_pubkey: key type ssh-rsa not in PubkeyAcceptedAlgorithms [preauth]
Good solution:
- generate new keys using a more secure algorithm like
ED25519
Lazy solution (acceptable for rsa keys with a length >= 3000bits):
- Execute:
sudo nano --backup /etc/ssh/sshd_config
- copy-paste the following into the above file:
PubkeyAcceptedAlgorithms=+ssh-rsa
- To save, press Ctrl+X Enter Y
It works now, but you’re still using SHA1 which has been showing weaknesses for years now (although it’s not actually cracked, it’s not recommended any more and why ssh disabled it)
QTile minimizes windows
floating_layout rules in a dict was deprecated a while ago
KDE Window Decorations UI with Drag&Drop broken
When going to System-Settings → Window Decorations → Titlebar Buttons the UI interface doesn’t allow you to drag and drop buttons any more.
Firefox mixes languages
- Clear your profile cache : Help → More troubleshooting information → Clear startup cache
- If that does not work, create a new profile. See here how to do so while keeping your bookmarks, extensions and customization.
Brave segfaults / crashes
Solution:
- Clear cache / Data
- Re-install Brave afterwards
You might have issues to install this update by missing Maintainers keys
A possible solution might be:
sudo rm -r /etc/pacman.d/gnupg
sudo pacman-key --init
sudo pacman-key --populate manjaro
sudo pacman-key --populate archlinux
sudo pacman -Syvv manjaro-keyring # just to test for key-problems, as this would fail
However, we recommend to remove the signatures of the failed packages in /var/cache/pacman/pkg/ and get the replaced ones from the Build-Server:
sudo rm -v /var/cache/pacman/pkg/*.sig
sudo pacman -Syvv
nVidia 4xx PRIME on kernel >= 5.5 has no audio
If you are using an nVidia card with the proprietary prime driver and you get no audio through the HDMI port or the USB devices of the card don’t work it’s because they have been disable due to a power management bug in the kernel. This bug has been fixed in recent updates, so if you are running a kernel with version >= 5.5 and the 4xx version nVidia driver you can fix those problems by editing the file /etc/udev/rules.d/90-mhwd-prime-powermanagement.rules and commenting the following lines in this way.
# Remove NVIDIA USB xHCI Host Controller devices, if present
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c0330", ATTR{remove}="1"
# Remove NVIDIA USB Type-C UCSI devices, if present
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c8000", ATTR{remove}="1"
# Remove NVIDIA Audio devices, if present
ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x040300", ATTR{remove}="1"
# Remove NVIDIA USB xHCI Host Controller devices, if present
#ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c0330", ATTR{remove}="1"
# Remove NVIDIA USB Type-C UCSI devices, if present
#ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x0c8000", ATTR{remove}="1"
# Remove NVIDIA Audio devices, if present
#ACTION=="add", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x040300", ATTR{remove}="1"
sudo sed -Ei '/"0x040300"/s/^/#/' /etc/udev/rules.d/90-mhwd-prime-powermanagement.rules
sudo sed -Ei '/"0x0c8000"/s/^/#/' /etc/udev/rules.d/90-mhwd-prime-powermanagement.rules
sudo sed -Ei '/"0x0c0330"/s/^/#/' /etc/udev/rules.d/90-mhwd-prime-powermanagement.rules
Freetype2 update may break applications
You might be blocked updating when using pacman due to some libcanberra packages.
Simply remove those packages:
sudo pacman -Rdd lib32-libcanberra-pulse \
lib32-libcanberra-gstreamer libcanberra-pulse libcanberra-gstreamer
Note: there are 4 packages to remove: copy all those two lines of the command.
We recommend to use pamac anyway, which does this automatically: pamac update
Compiz packages got dropped from our repositories
wget now always outputs “SSL_INIT” to stderr every time it is run.
Issue tracked here: GNU Wget - Bugs: bug #61125
vboxdrv error messages of systemd from log journactl -b -p 3
I got the error messages of systemd from log journactl -b -p 3 after this update:
systemd-udevd[329]: vboxdrv: /usr/lib/udev/rules.d/60-vboxdrv.rules:1 Only network interfaces can be renamed, ignoring NAME="vboxdrv".
systemd-udevd[335]: vboxdrvu: /usr/lib/udev/rules.d/60-vboxdrv.rules:2 Only network interfaces can be renamed, ignoring NAME="vboxdrvu".
systemd-udevd[338]: vboxnetctl: /usr/lib/udev/rules.d/60-vboxdrv.rules:3 Only network interfaces can be renamed, ignoring NAME="vboxnetctl".
systemd-udevd[322]: vboxdrv: /usr/lib/udev/rules.d/60-vboxdrv.rules:1 Only network interfaces can be renamed, ignoring NAME="vboxdrv".
systemd-udevd[343]: vboxdrvu: /usr/lib/udev/rules.d/60-vboxdrv.rules:2 Only network interfaces can be renamed, ignoring NAME="vboxdrvu"..
Solution:
Edit the file /lib/udev/rules.d/60-vboxdrv.rules
#KERNEL=="vboxdrv", NAME="vboxdrv", OWNER="root", GROUP="root", MODE="0600"
#KERNEL=="vboxdrvu", NAME="vboxdrvu", OWNER="root", GROUP="root", MODE="0666"
#KERNEL=="vboxnetctl", NAME="vboxnetctl", OWNER="root", GROUP="root", MODE="0600"
KERNEL=="vboxdrv", OWNER="root", GROUP="root", MODE="0600"
KERNEL=="vboxdrvu", OWNER="root", GROUP="root", MODE="0666"
KERNEL=="vboxnetctl", OWNER="root", GROUP="root", MODE="0600"
SUBSYSTEM=="usb_device", ACTION=="add", RUN+="/usr/share/virtualbox/VBoxCreateUSBNode.sh $major $minor $attr{bDeviceClass} vboxusers"
SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", RUN+="/usr/share/virtualbox/VBoxCreateUSBNode.sh $major $minor $attr{bDeviceClass} vboxusers"
SUBSYSTEM=="usb_device", ACTION=="remove", RUN+="/usr/share/virtualbox/VBoxCreateUSBNode.sh --remove $major $minor"
SUBSYSTEM=="usb", ACTION=="remove", ENV{DEVTYPE}=="usb_device", RUN+="/usr/share/virtualbox/VBoxCreateUSBNode.sh --remove $major $minor"
or ignore these messages from the log.
Firefox VAAPI doesn’t work