Dark theme in Dom

[taran1s]

Hello everyone, I am trying to set up the dark theme in dom0. All
working well but at the end it doesnt work. There are some errors
popping up and I think this is the issue but duno how to solve that.

[xxx@dom0 ~]$ sudo qubes-dom0-update qt5-qtstyleplugins
Using sys-whonix-update as UpdateVM to download updates for Dom0; this
may take some time...
Qubes OS Repository for Dom0 0.0 B/s | 0 B
00:00
Errors during downloading metadata for repository 'qubes-dom0-cached':
- Curl error (37): Couldn't read a file:// file for
file:///var/lib/qubes/updates/repodata/repomd.xml [Couldn't open file
/var/lib/qubes/updates/repodata/repomd.xml]
Error: Failed to download metadata for repo 'qubes-dom0-cached': Cannot
download repomd.xml: Cannot download repodata/repomd.xml: All mirrors
were tried
Ignoring repositories: qubes-dom0-cached
Package qt5-qtstyleplugins-5.0.0-39.fc32.x86_64 is already installed.
Dependencies resolved.
Nothing to do.
Complete!

[guruji@dom0 ~]$ export QT_QPA_PLATFORMTHEME=gtk2 /etc/environment
bash: export: `/etc/environment': not a valid identifier

#Due to error above I did it manually:
sudo nano /etc/environment ## added QT_QPA_PLATFORMTHEME=gtk2

[xxx@dom0 ~]$ cat /etc/environment
QT_QPA_PLATFORMTHEME=gtk2

[xxx@dom0 ~]$ echo $QT_QPA_PLATFORMTHEME
gtk2

[xxx@dom0 ~]$ sudo dnf info qt5-qtstyleplugins
Qubes OS Repository for Dom0 0.0 B/s | 0 B
00:00
Errors during downloading metadata for repository 'qubes-dom0-cached':
- Curl error (37): Couldn't read a file:// file for
file:///var/lib/qubes/updates/repodata/repomd.xml [Couldn't open file
/var/lib/qubes/updates/repodata/repomd.xml]
Error: Failed to download metadata for repo 'qubes-dom0-cached': Cannot
download repomd.xml: Cannot download repodata/repomd.xml: All mirrors
were tried
Ignoring repositories: qubes-dom0-cached
Installed Packages
Name : qt5-qtstyleplugins
Version : 5.0.0
Release : 39.fc32
Architecture : x86_64
Size : 1.2 M
Source : qt5-qtstyleplugins-5.0.0-39.fc32.src.rpm
Repository : @System
From repo : qubes-dom0-cached
Summary : Classic Qt widget styles
URL : https://github.com/qtproject/qtstyleplugins
License : LGPLv2 or GPLv2
Description : Classic Qt widget styles, including cleanlooks, motif,
plastique,
: qgtk.

Any ideas?