Same for me but on Gnome.

😞

I'm having the same issue on Linux Mint 19.2 Cinnamon desktop. Uninstalling then reinstalling (including a new configuration file) doesn't help. Happens with both manual and automatic location settings.

Right-clicking the icon I have pinned to my desktop panel and manually selecting 'Run AutomaThemely' works just fine.

I have just replaced AutomaThemely with a simple script that i made a keyboard shortcut for, simpler and always works, as AutomaThemely is not 'auto' for me.

@MuathAmer, would you mind posting your code?

@neekt It's for gnome so i don't know how it can help.
https://github.com/MuathAmer/mythemely

Thanks anyway, appreciated!

Another simple way I discovered for automating theme changes is to use Sunwait.

Once that's installed, you can set up cron jobs, something like (using your own lat/long and shell script locations):
00 16 * * * sunwait wait set 51.477932N 0.000000E; /home/<user>/scripts/night_themes.sh
0 4 * * * sunwait wait rise 51.477932N 0.000000E; /home/<user>/scripts/day_themes.sh

Where night_themes.sh contains something like this (on Linux Mint Cinnamon, for example):

gsettings set org.cinnamon.desktop.wm.preferences theme Mint-Y-Dark
gsettings set org.cinnamon.desktop.interface gtk-theme Mint-Y-Dark
gsettings set org.cinnamon.theme name Mint-Y-Dark

To change Window borders, Controls, and Desktop themes, respectively.

And because Ubuntu/Mint uses anacron by default, it should work even if the computer is powered off or sleeping at the time of the scheduled jobs, although I haven't actually tested this.

Thanks its good idea, but currently sticking with manually setting, as I found I am rarely using dark theme at night, and automathemely has nice ui to set things up.

I would like to add that it doesn't seem to automatically run on bog standard Ubuntu 19.10 either.

Might be something with python's scheduler, or maybe something with the systemd service.
If still relevant, would you be able to show the output of running systemctl list-timers?

I'm very sorry :S

I am on Ubuntu MATE 20.04 now, so it isn't the same situation. Anyway, the output of systemctl list-timers is:

NEXT                        LEFT          LAST                        PASSED       UNIT                         ACTIVATES                     
Mon 2020-04-13 02:01:14 BST 1h 20min left Sun 2020-04-12 14:06:31 BST 10h ago      motd-news.timer              motd-news.service             
Mon 2020-04-13 06:50:32 BST 6h left       Sun 2020-04-12 14:06:31 BST 10h ago      apt-daily-upgrade.timer      apt-daily-upgrade.service     
Mon 2020-04-13 09:23:52 BST 8h left       Sun 2020-04-12 18:45:02 BST 5h 55min ago fwupd-refresh.timer          fwupd-refresh.service         
Mon 2020-04-13 15:11:00 BST 14h left      Sun 2020-04-12 20:55:28 BST 3h 45min ago apt-daily.timer              apt-daily.service             
Mon 2020-04-13 19:36:20 BST 18h left      Sun 2020-04-12 16:41:28 BST 7h ago       systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service
Tue 2020-04-14 00:00:00 BST 23h left      Mon 2020-04-13 00:37:28 BST 3min 15s ago logrotate.timer              logrotate.service             
Tue 2020-04-14 00:00:00 BST 23h left      Mon 2020-04-13 00:37:28 BST 3min 15s ago man-db.timer                 man-db.service                
Sun 2020-04-19 03:10:54 BST 6 days left   Sun 2020-04-12 14:06:31 BST 10h ago      e2scrub_all.timer            e2scrub_all.service           
Mon 2020-04-20 00:00:00 BST 6 days left   Mon 2020-04-13 00:37:28 BST 3min 15s ago fstrim.timer                 fstrim.service                
n/a                         n/a           Mon 2020-04-13 00:37:28 BST 3min 15s ago anacron.timer                anacron.service               

10 timers listed.
Pass --all to see loaded but inactive timers, too.

I don't have AutomaThemely installed currently, which presumably will affect these results.