plasma5 activation scripts fails with unset/null XDG_CONFIG_HOME

[pio2398]

Describe the bug
After upgrade to 20.03 nixos-activation.service don't start .

Error log:
● nixos-activation.service - Run user-specific NixOS activation
Loaded: loaded (/nix/store/jcv2nvwkdc4hlhfx2dcchw3xgnmgyk8n-unit-nixos-activation.service/nixos-activation.service; static; vendor preset: enabled)
Active: failed (Result: exit-code) since Fri 2020-02-21 11:57:14 CET; 8s ago
Process: 11052 ExecStart=/nix/store/6hls8gx0c7prqf6gc2s1q9kp5w57jnb4-unit-script-nixos-activation-start (code=exited, status=1/FAILURE)
Main PID: 11052 (code=exited, status=1/FAILURE)

lut 21 11:57:14 nixos systemd[1389]: Starting Run user-specific NixOS activation...
lut 21 11:57:14 nixos 6hls8gx0c7prqf6gc2s1q9kp5w57jnb4-unit-script-nixos-activation-start[11052]: /nix/store/6hls8gx0c7prqf6gc2s1q9kp5w57jnb4-unit-script-nixos-activation-start: line 22: XDG_CONFIG_HOME: parameter null or not set
lut 21 11:57:14 nixos systemd[1389]: nixos-activation.service: Main process exited, code=exited, status=1/FAILURE
lut 21 11:57:14 nixos systemd[1389]: nixos-activation.service: Failed with result 'exit-code'.
lut 21 11:57:14 nixos systemd[1389]: Failed to start Run user-specific NixOS activation.

I am using home manager but empty profile without home manager is also broken. After switch channel to 19.09 everything is OK.

To Reproduce
Steps to reproduce the behavior:

1. Upgrade to 20.03

Additional context
I am using KDE. Adding XDG_CONFIG_HOME to this file does not solve the problem completely. Service start but for ex. flatpak app not.

Metadata
Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.
nix-shell -p nix-info --run "nix-info -m"

• system: "x86_64-linux"
• host os: Linux 5.4.19, NixOS, 20.03beta-475.71be729a58e (Markhor)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.2
• channels(root): "nixos-20.03beta-475.71be729a58e"
• channels(piotrek): "home-manager, nixos-20.03pre212208.8130f3c1c2b, nixpkgs-20.03pre212208.8130f3c1c2b"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module:

[AtkinsChang]

caused by d5757a8

[ghost]

I had this issue too, and it can be fixed by enabling this :

services = {
  dbus.socketActivated = true;
  xserver.startDbusSession = false;
}

I am not really sure why, this fix come from another issue that is plasma related.

[worldofpeace]

cc @ttuegel

[pio2398]

@elyhaka: Yes, it's solve error related to XDG_CONFIG_HOME but flatpak app still fail to launch. Starting KeePassXC result in error: The name org.freedesktop.Accounts was not provided by any .service files. Unrelated problem?
EDIT:
Yes, it's https://discourse.nixos.org/t/flatpak-error-the-name-org-freedesktop-accounts-was-not-provided-by-any-service-file/6000/8

[mdedetrich]

@elyhaka As far as I understand this is actually a workaround and not a real solution. iirc the suggested workaround was for a now fixed problem where plasma wouldn't start due to a hardcoded limit on env vars

[ghost]

It is indeed a workaround, sorry for the bad phrasing. I know this is a workaround for another issue that has been merged, but it has fixed the issue for me.