Unable to determine socket to daemon: cannot login (even if I append X-LightDM-Allow-Greeter=true to my session file)

[Mibanfi]

Environment

• OS: Arch Linux
• web-greeter version: 3.5.2

Bug description

Hello!
First of all, thank you for your hard work. I am glad a program like this exists.
I have been facing an issue where I can open the greeter and it works normally, but it seems unable to access the session's file. This happens both when I test the greeter through a terminal emulator and when I load it normally through the lightdm service. The same error happens on nody-greeter. I have tried both the default theme, gruvbox, and mshernandez5's WelcomeXP, to the same result.
The bug happens regardless of appending X-LightDM-Allow-Greeter=true to my session file.

Interestingly enough, the only way I could achieve a slightly different result was by not setting any user session in lightdm.conf (which leads the greeter to use the default session), then creating a default.desktop file in /usr/share/xsessions/. When I do this and try to log in, instead of showing an error message, the screen goes black for a few seconds, only to reload the greeter from the start. I am unsure why this specific scenario happens.
Could you kindly lend me your aid? I have been stuck here for a long while.
Thank you in advance!

Steps to reproduce

Try to login and insert the correct password. Alternatively, a similar error message can be seen by running web-greeter in a terminal emulator.

Expected behavior

Booting the session normally.

Screenshots