[SOLVED] Mint 20 Cinnamon boots into gdm + Gnome, no network

[argail]

Hi there,

my Mint Cinnamon 20.1 boots into that ubuntu-purple gdm greeter and starts gnome-shell when I log in. I have no option to change the desktop and no network at all. I can change into a tty, also no luck from there, I can't even ping my router. My data seems to be there and all the drives are mounted correctly, but gnome complains that the network-manager is not started.
I tried to apt reinstall network-manager but that tells me network-manager is not installed and wants to uninstall a bunch of stuff like gconf-services, libc++1-10 etc. and I didn't want to break my system even more. I also managed to boot from a live stick, the live system has network and everything, so i did an apt update via chroot on my system drive, that seems to have worked but did not solve the problem. I could reboot into my system but still have neither network nor cinnamon.

Things I did just before that hapened:
I tried to install virt-manager and qemu, no errors. virt-manager complained that libvirtd wasn't started. After that i noticed a strange error in the update-manager. There was an update (forgot which one) but the "install updaes" butten was grayed out until I unchecked and rechekched the update. After that I could click the install button but it did nothing. I rebooted because I thought that would start libvirtd and I thought i could fix the strange update error by apt update from the terminal later, but apparently that was a bad idea.

This is the strangest error I ever had, I do not even remember installing gnome shell at all. Any help is very much appreciated.


Linux Mint 20.1
Kernel 5.4.0-94-generic

[valouch]

Gdm3 installs "minimal gnome" named ubuntu; however, you can easily switch back to cinnamon - see the picture. And if you want to use rather lightdm, type the command sudo dpkg-reconfigure lightdm.
Lost network connectivity is different not related problem.

[argail]

Hi, thanks for the answer. I have already tried dpkg-reconfigure lightdm, it says lightdm is not installed. And on the greeter there are no desktop settings at all, just the Shutdown/restart and the accessibility settings. I assume the last update broke something or did not run properly and what I see is a kind of emergency fallback

[valouch]

it says lightdm is not installed

apt install lightdm lightdm-settings slick-greeter

there are no desktop settings at all

Damaged system, or not a mint at all... best to revert back to previous working state or reinstall.

[argail]

Damaged system, or not a mint at all... best to revert back to previous working state or reinstall.

I am quite sure i have not accidentally installed another Distro and I don't want to use the club-on-the-head solution just yet.

However, I had a look in the aptitude logs and found that something actually uninstalled some packages that look like they should not have been uninstalled. The time corresponds to when I installed virt-manager via the software-manager GUI:

/var/log/apt/history.log:

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Start-Date: 2022-01-14  12:47:51
Commandline: aptdaemon role='role-install-packages' sender=':1.257'
Install: libpam0g:i386 (1.3.1-5ubuntu4.3, automatic), libusbredirparser1:amd64 (0.8.0-1), seabios:amd64 (1.13.0-1ubuntu1.1), libdevmapper1.02.1:i386 (2:1.02.167-1ubuntu1, automatic), gnome-control-center-data:amd64 (1:3.36.5-0ubuntu3, automatic), libgovirt2:amd64 (0.3.4-3.1), libseccomp2:i386 (2.5.1-1ubuntu1~20.04.2, automatic), virtinst:amd64 (1:2.2.1-3ubuntu2.1), gnome-session-common:amd64 (3.36.0-2ubuntu1, automatic), osinfo-db:amd64 (0.20200325-1), gir1.2-mutter-6:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), ipxe-qemu:amd64 (1.0.0+git-20190109.133f4c4-0ubuntu3.2), gnome-control-center:amd64 (1:3.36.5-0ubuntu3, automatic), libxml2-utils:amd64 (2.9.10+dfsg-5ubuntu0.20.04.1), libvirt-daemon-system-systemd:amd64 (6.0.0-0ubuntu8.15), gir1.2-spiceclientgtk-3.0:amd64 (0.37-2fakesync1), gnome-user-docs:amd64 (3.36.2+git20200704-0ubuntu0.1, automatic), libargon2-1:i386 (0~20171227-0.2, automatic), libosinfo-1.0-0:amd64 (1.7.1-1), spice-client-glib-usb-acl-helper:amd64 (0.37-2fakesync1), libpam-fprintd:amd64 (1.90.9-1~ubuntu20.04.1, automatic), msr-tools:amd64 (1.3-3), libacl1:i386 (2.2.53-6, automatic), libkmod2:i386 (27-1ubuntu2, automatic), libwhoopsie0:amd64 (0.2.69ubuntu0.3, automatic), language-selector-common:amd64 (0.204.2, automatic), librbd1:amd64 (15.2.14-0ubuntu0.20.04.2), ubuntu-wallpapers-focal:amd64 (20.04.2-0ubuntu1, automatic), ubuntu-session:amd64 (3.36.0-2ubuntu1, automatic), qemu-system-x86:amd64 (1:4.2-3ubuntu6.19), python3-libxml2:amd64 (2.9.10+dfsg-5ubuntu0.20.04.1), libusbredirhost1:amd64 (0.8.0-1), libvirt-clients:amd64 (6.0.0-0ubuntu8.15), libwhoopsie-preferences0:amd64 (22, automatic), whoopsie-preferences:amd64 (22, automatic), libnss-mymachines:amd64 (245.4-4ubuntu3.15), gdm3:amd64 (3.36.3-0ubuntu0.20.04.4, automatic), libspice-server1:amd64 (0.14.2-4ubuntu3.1), libvirt-daemon-driver-storage-rbd:amd64 (6.0.0-0ubuntu8.15), libmutter-6-0:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), librygel-server-2.6-2:amd64 (0.38.3-1ubuntu1, automatic), libpmem1:amd64 (1.8-1ubuntu1), libphodav-2.0-common:amd64 (2.4-1), gir1.2-gdm-1.0:amd64 (3.36.3-0ubuntu0.20.04.4, automatic), libgovirt-common:amd64 (0.3.4-3.1), mutter-common:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), systemd-timesyncd:i386 (245.4-4ubuntu3.15, automatic), ovmf:amd64 (0~20191122.bd85bf54-2ubuntu3.3), libvirglrenderer1:amd64 (0.8.2-1ubuntu1), librygel-db-2.6-2:amd64 (0.38.3-1ubuntu1, automatic), libgdm1:amd64 (3.36.3-0ubuntu0.20.04.4, automatic), gir1.2-gck-1:amd64 (3.36.0-2build1, automatic), libmediaart-2.0-0:amd64 (1.9.4-2, automatic), libgnome-autoar-0-0:amd64 (0.2.3-2ubuntu0.4, automatic), ubuntu-docs:amd64 (20.04.3, automatic), gir1.2-graphene-1.0:amd64 (1.10.0-1build2, automatic), libgvnc-1.0-0:amd64 (1.0.0-1build1), libvirt-daemon-driver-qemu:amd64 (6.0.0-0ubuntu8.15), qemu-system-data:amd64 (1:4.2-3ubuntu6.19), qemu-utils:amd64 (1:4.2-3ubuntu6.19), libvirt-daemon-system:amd64 (6.0.0-0ubuntu8.15), libcacard0:amd64 (1:2.6.1-1), gir1.2-gtk-vnc-2.0:amd64 (1.0.0-1build1), gnome-shell-common:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), gir1.2-gcr-3:amd64 (3.36.0-2build1, automatic), sharutils:amd64 (1:4.15.2-4build1), ipxe-qemu-256k-compat-efi-roms:amd64 (1.0.0+git-20150424.a25a16d-0ubuntu4), virt-manager:amd64 (1:2.2.1-3ubuntu2.1), virt-viewer:amd64 (7.0-2build1), systemd:i386 (245.4-4ubuntu3.15, automatic), rygel:amd64 (0.38.3-1ubuntu1, automatic), libspice-client-glib-2.0-8:amd64 (0.37-2fakesync1), yaru-theme-gnome-shell:amd64 (20.04.11.1, automatic), libvirt-glib-1.0-0:amd64 (3.0.0-1), qemu-kvm:amd64 (1:4.2-3ubuntu6.19), libvirt0:amd64 (6.0.0-0ubuntu8.15), libcheese-gtk25:amd64 (3.34.0-1ubuntu1, automatic), libgsound0:amd64 (1.0.2-4, automatic), cheese-common:amd64 (3.34.0-1ubuntu1, automatic), switcheroo-control:amd64 (2.1-1, automatic), libcolord-gtk1:amd64 (0.2.0-0ubuntu1, automatic), gnome-control-center-faces:amd64 (1:3.36.5-0ubuntu3, automatic), libcap-ng0:i386 (0.7.9-2.1build1, automatic), ubuntu-wallpapers:amd64 (20.04.2-0ubuntu1, automatic), libfdt1:amd64 (1.5.1-1), libslirp0:amd64 (4.1.0-2ubuntu2.2), libiscsi7:amd64 (1.18.0-2), libgupnp-dlna-2.0-3:amd64 (0.10.5-4, automatic), libphodav-2.0-0:amd64 (2.4-1), python3-libvirt:amd64 (6.1.0-1), libcheese8:amd64 (3.34.0-1ubuntu1, automatic), systemd-container:amd64 (245.4-4ubuntu3.15), cpu-checker:amd64 (0.7-1.1), gnome-shell:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), libcryptsetup12:i386 (2:2.2.2-3ubuntu2.3, automatic), librygel-core-2.6-2:amd64 (0.38.3-1ubuntu1, automatic), librygel-renderer-2.6-2:amd64 (0.38.3-1ubuntu1, automatic), language-selector-gnome:amd64 (0.204.2, automatic), libjson-c4:i386 (0.13.1+dfsg-7ubuntu0.3, automatic), gir1.2-libvirt-glib-1.0:amd64 (3.0.0-1), libip4tc2:i386 (1.8.4-3ubuntu2, automatic), qemu-block-extra:amd64 (1:4.2-3ubuntu6.19), libgupnp-av-1.0-2:amd64 (0.12.11-2, automatic), gir1.2-rsvg-2.0:amd64 (2.48.9-1ubuntu0.20.04.1, automatic), gir1.2-libosinfo-1.0:amd64 (1.7.1-1), libspice-client-gtk-3.0-5:amd64 (0.37-2fakesync1), librados2:amd64 (15.2.14-0ubuntu0.20.04.2), libgtk-vnc-2.0-0:amd64 (1.0.0-1build1), qemu-system-common:amd64 (1:4.2-3ubuntu6.19), gir1.2-spiceclientglib-2.0:amd64 (0.37-2fakesync1), libaudit1:i386 (1:2.8.5-2ubuntu6, automatic), qemu-system-gui:amd64 (1:4.2-3ubuntu6.19), mutter:amd64 (3.36.9-0ubuntu0.20.04.2, automatic), libvirt-daemon:amd64 (6.0.0-0ubuntu8.15)
Upgrade: libseccomp2:amd64 (2.5.1-1ubuntu1~20.04.1, 2.5.1-1ubuntu1~20.04.2), libsystemd0:amd64 (245.4-4ubuntu3.13, 245.4-4ubuntu3.15), libsystemd0:i386 (245.4-4ubuntu3.13, 245.4-4ubuntu3.15), systemd-sysv:amd64 (245.4-4ubuntu3.13, 245.4-4ubuntu3.15), libpam-systemd:amd64 (245.4-4ubuntu3.13, 245.4-4ubuntu3.15)
Remove: libkf5kiowidgets5:amd64 (5.68.0-0ubuntu1), network-manager-pptp:amd64 (1.2.8-2), mintwelcome:amd64 (2.5.0), netplan.io:amd64 (0.103-0ubuntu5~20.04.5), gvfs-backends:amd64 (1.44.1-1ubuntu1), slick-greeter:amd64 (1.5.2+ulyssa), apturl-common:amd64 (0.5.2+linuxmint11), rtkit:amd64 (0.12-4), policykit-1-gnome:amd64 (0.105-7ubuntu2), systemd-coredump:amd64 (245.4-4ubuntu3.13), mate-panel:amd64 (1.24.0-2), mate-polkit:amd64 (1.24.0-2), plymouth-label:amd64 (0.9.4+mint2+ulyssa), nemo-share:amd64 (4.6.0+ulyana), plymouth-theme-ubuntu-text:amd64 (0.9.4+mint2+ulyssa), network-manager-gnome:amd64 (1.8.24-linuxmint4), nemo:amd64 (4.8.6+ulyssa), network-manager:amd64 (1.22.10-1ubuntu2.2), packagekit-tools:amd64 (1.1.13-2ubuntu1.1), kio:amd64 (5.68.0-0ubuntu1), mint-meta-cinnamon:amd64 (2021.01.02), cinnamon-control-center-dbg:amd64 (4.8.2+ulyssa), gnome-disk-utility:amd64 (3.36.3-0ubuntu1), systemd-timesyncd:amd64 (245.4-4ubuntu3.13), apturl:amd64 (0.5.2+linuxmint11), cinnamon-dbg:amd64 (4.8.6+ulyssa), cinnamon-control-center:amd64 (4.8.2+ulyssa), ubuntu-minimal:amd64 (1.450.2), udisks2:amd64 (2.8.4-1ubuntu2), gvfs-fuse:amd64 (1.44.1-1ubuntu1), nemo-fileroller:amd64 (4.6.0+ulyana), nemo-dbg:amd64 (4.8.6+ulyssa), network-manager-openvpn:amd64 (1.8.12-1), mint-meta-core:amd64 (2021.01.02), mintdrivers:amd64 (1.5.8), packagekit:amd64 (1.1.13-2ubuntu1.1), systemd:amd64 (245.4-4ubuntu3.13), mintupdate:amd64 (5.7.8), libnss-systemd:amd64 (245.4-4ubuntu3.13), nemo-preview:amd64 (4.6.0+ulyana), network-manager-config-connectivity-ubuntu:amd64 (1.22.10-1ubuntu2.2), plymouth:amd64 (0.9.4+mint2+ulyssa), gvfs:amd64 (1.44.1-1ubuntu1), labplot:amd64 (2.7.0-1build2), cinnamon:amd64 (4.8.6+ulyssa), network-manager-openvpn-gnome:amd64 (1.8.12-1), synaptic:amd64 (0.84.6linuxmint2), gstreamer1.0-packagekit:amd64 (1.1.13-2ubuntu1.1), libkf5kiocore5:amd64 (5.68.0-0ubuntu1), network-manager-pptp-gnome:amd64 (1.2.8-2), gvfs-daemons:amd64 (1.44.1-1ubuntu1), lightdm:amd64 (1.30.0-0ubuntu4~20.04.1)
End-Date: 2022-01-14  12:49:21

And here is /var/log/apt/term.log:

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Log started: 2022-01-14  12:47:51
(Reading database ... 
(Reading database ... 5%
(Reading database ... 10%
(Reading database ... 15%
(Reading database ... 20%
(Reading database ... 25%
(Reading database ... 30%
(Reading database ... 35%
(Reading database ... 40%
(Reading database ... 45%
(Reading database ... 50%
(Reading database ... 55%
(Reading database ... 60%
(Reading database ... 65%
(Reading database ... 70%
(Reading database ... 75%
(Reading database ... 80%
(Reading database ... 85%
(Reading database ... 90%
(Reading database ... 95%
(Reading database ... 100%
(Reading database ... 932019 files and directories currently installed.)
Removing mint-meta-cinnamon (2021.01.02) ...
Removing mint-meta-core (2021.01.02) ...
Removing mintwelcome (2.5.0) ...
Removing apturl (0.5.2+linuxmint11) ...
Removing apturl-common (0.5.2+linuxmint11) ...
Removing cinnamon-dbg (4.8.6+ulyssa) ...
Removing cinnamon (4.8.6+ulyssa) ...
Removing cinnamon-control-center-dbg (4.8.2+ulyssa) ...
Removing cinnamon-control-center (4.8.2+ulyssa) ...
Removing gnome-disk-utility (3.36.3-0ubuntu1) ...
Removing gstreamer1.0-packagekit (1.1.13-2ubuntu1.1) ...
Removing gvfs-backends (1.44.1-1ubuntu1) ...
Removing nemo-fileroller (4.6.0+ulyana) ...
Removing gvfs-fuse (1.44.1-1ubuntu1) ...
Removing labplot (2.7.0-1build2) ...
Removing kio (5.68.0-0ubuntu1) ...
Removing libkf5kiowidgets5:amd64 (5.68.0-0ubuntu1) ...
Removing libkf5kiocore5:amd64 (5.68.0-0ubuntu1) ...
Removing libnss-systemd:amd64 (245.4-4ubuntu3.13) ...
Checking NSS setup...
Removing slick-greeter (1.5.2+ulyssa) ...
Removing lightdm (1.30.0-0ubuntu4~20.04.1) ...
Removing mate-panel (1.24.0-2) ...
Removing network-manager-gnome (1.8.24-linuxmint4) ...

To me, that smells strongly of dependency bug like the one in here (10:08): https://www.youtube.com/watch?v=0506yDSgU7M

So, next I'll try to reinstall mint-meta-core and mint-meta-cinnamon... wish me luck folks

[smurphos]

Try this command to simulate what would happen if you tried to reinstall cinnamon. If output look OK, use it without the -s flag.

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sudo apt install -s mint-meta-cinnamon

[argail]

Will do, thank you.

[argail]

So, that was a partial success. I can now choose cinnamon from the greeter but still have no networking going. I identified the packages that were uninstalled but the last command did not reinstall. Also on my system

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networkctl

outputs the correct interfaces, but they are all marked as unmanaged. There might be some config in one of the packages that are still missing (list below)

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kio:amd64 (5.68.0-0ubuntu1), 
labplot:amd64 (2.7.0-1build2), 
libkf5kiocore5:amd64 (5.68.0-0ubuntu1), 
libkf5kiowidgets5:amd64 (5.68.0-0ubuntu1), 
libnss-systemd:amd64 (245.4-4ubuntu3.13), 
lightdm:amd64 (1.30.0-0ubuntu4~20.04.1)
nemo-dbg:amd64 (4.8.6+ulyssa), 
nemo-preview:amd64 (4.6.0+ulyana), 
nemo-share:amd64 (4.6.0+ulyana), 
netplan.io:amd64 (0.103-0ubuntu5~20.04.5), 
network-manager-config-connectivity-ubuntu:amd64 (1.22.10-1ubuntu2.2), 
network-manager-openvpn-gnome:amd64 (1.8.12-1), 
network-manager-openvpn:amd64 (1.8.12-1), 
plymouth-label:amd64 (0.9.4+mint2+ulyssa), 
rtkit:amd64 (0.12-4), 
slick-greeter:amd64 (1.5.2+ulyssa), 
systemd-coredump:amd64 (245.4-4ubuntu3.13), 
systemd-timesyncd:amd64 (245.4-4ubuntu3.13), 
systemd:amd64 (245.4-4ubuntu3.13), 
ubuntu-minimal:amd64 (1.450.2), 

Right now I'm in a live system installing all the missing packages (apart from labplot etc.) via chroot, at least that should give me my greeter back...

[argail]

Aaaand we're back in business. Thanks.
I'll let you know if I can reproduce that error in a VM

[Hoser Rob]

Damaged system, or not a mint at all... best to revert back to previous working state or reinstall.

I am quite sure i have not accidentally installed another Distro and I don't want to use the club-on-the-head solution just yet....

Personally I'd suggest reintalling, IMHO you have so thoroughly borked your OS that a clean reinstall is probably the fastest and easiest way to fix it. This is why I'm always saying it's a bad idea to add multiple DEs here..

[valouch]

However, I had a look in the aptitude logs and found that something actually uninstalled some packages that look like they should not have been uninstalled.

I'll let you know if I can reproduce that error in a VM

Tested kvm + qenu + vmm installation via
apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virtinst virt-manager
in uma cinnamon; no problem, no error messages, zero uninstalled packages. I can only guess what was wrong with your system; I think either apt cache is corrupted or wrong custom repository is added - it can manifest itself anytime in the future. Or youy followed some very bad howto.

I identified the packages that were uninstalled but the last command did not reinstall

Right now I'm in a live system installing all the missing packages (apart from labplot etc.) via chroot

Well done; try to install all removed packages again.

This is why I'm always saying it's a bad idea to add multiple DEs here..

I do not agree. Routinely using multiple desktop managers and desktop environments without problems.

[argail]

This is why I'm always saying it's a bad idea to add multiple DEs here..

Just for the record, I have not installed gdm or gnome intentionally. But I agree that you shouldn't do that. The result is often messy in my experience.

However, I've been able to reproduce that error in a VM:

VirtualBox 6.1.26_Ubuntu, on Host LInux Mint 20.1 64bit with guest Linux Mint 20.3. 64bit

Steps to reproduce:
1. Install 20.3 64bit via Live-iso
2. Install virt-manager via Software Management GUI
3. reboot

This dropped me into tty1 without display manager at all. There was a list of packages that were to be removed. So, technically, it said what it was about to do,
but a beginner will not know that they're going to mess up their system really bad if they don't know what those packages do.

Tested kvm + qenu + vmm installation via

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 apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virtinst virt-manager

That's interesting, I will check if the error also occurs via command line.

[smurphos]

I just tried in a 20.3 Cinnamon VM via Software manager and can't reproduce what you are seeing. It would be interesting to see the full output of an attempt to install via the command line on your machine.

Use apt install -s virt-manager (has the simulate flag)

Edit to add - just tried some experiments.

Freshly booted 20.3 Cinnamon live session

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apt update && apt install -s virt-manager 

- no unexpected package removals listed. Selecting it for install in synaptic also produces no unexpected output. But then opening software manager to try and install it does list mass removals - intriguing.

On a freshly installed 20.3 cinnamon in Vbox slightly different results. Command line and Synaptic have expected results, but Software manager refuses to install due to unmet dependencies (wrong versions of systemd will be installed). If I then open update manager and update the system, Software Manager will install it fine with no package removals.

My take home is some buggy behaviour in Software Manager - 1) It's not updating it's cache properly, and b) it's not dealing with dependencies that have pending upgrades properly in the same way as apt in the command line or Synaptic do.

Probably related - https://github.com/linuxmint/mintinstall/issues/317

[argail]

I can confirm that a fresh install in a VM does not produce the error when I install via apt like so:

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apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virtinst virt-manager

also, no funny output when installing just virt-manager on my (real) machine:

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root@xyz-PC-Linux:/home/xyz# LC_ALL=C apt install -s virt-manager
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  python3-guestfs ssh-askpass
The following NEW packages will be installed:
  virt-manager
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Inst virt-manager (1:2.2.1-3ubuntu2.1 Ubuntu:20.04/focal-updates [all])
Conf virt-manager (1:2.2.1-3ubuntu2.1 Ubuntu:20.04/focal-updates [all])
root@xyz-PC-Linux:/home/xyz#

This is quite strange...

OK, i have now tried several configs. In qemu-VMs I get another error (dependency conflict with systemd) via the software manager and no error via apt. In Virtualbox I get the error I initially had but again, no error via apt. An update/upgrade gets rid of the error.

I must have caught a very bad time between updates in the first place.

btw, there is a comment in the software manager at the moment of a guy complaining that virt-manager broke his system.

read your edit just now. Sounds roughly what I experienced. Happy that I'm not crazy

[valouch]

Installed 20.1 in VM, applied all patches, tested virt-manager installation using 1. apt 2. synaptic 3. software manager. No uninstalled packages, no errors in all cases.

Please share output of inxi -Fxxrzc0 taken from affected system.

[smurphos]

applied all patches...

The problem appears to be anomalous behaviour in Software Manager when there are pending updates. I can imagine some new inexperienced user ignoring the Welcome Screen app and that the Update Manager icon is flagging it needs attention and plowing straight into discovering what's available in Software Manager, possibly with not great results depending on what they try and install. Apt and Synaptic deal with this gracefully - any dependency with a pending update gets updated as part of the install process. Software manager doesn't seem to do this on limited testing thus far.

[argail]

Please share output of

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inxi -Fxxrzc0

taken from affected system.

Sorry, can't. Installation works fine now. I guess I had some pending updates but those were max. 1-2 days old, I installed my system a while ago and did regular updates.

The problem appears to be anomalous behaviour in Software Manager when there are pending updates.

Seems to me you're right. I know that Manjaro is likely to dump you in the bog if you don't do your updates before installing a package but I never had this issue with apt or synaptic. And let's face it: anyone can forget that once in a while.

[valouch]

The problem appears to be anomalous behaviour in Software Manager when there are pending updates

Confirmed; you are definitely right. Very dangerous bug.