Plasma - missing deskop icons preview and folder thumbnails

[Daedalus]

Hey,

I have a very peculiar problem related to showing icons preview on a desktop as well as folder thumbnails.

1. Missing desktops icons preview

Image files on a desktop have no preview. The option under: Context menu → Icons → Show Previews is checked (including preview plugins)

What’s more interesting, if I browse desktop files through Dolphin all the previews are displayed correctly

2. Folders which contain graphic files have no these little thumbnails on a folder icon.

Again: Configure Dolphin → Interface → Preview → most of the types including folders are checked.

I’m quite sure these all worked in the past but it stopped at some point of time. Reinstalling plasma, os, cleaning plasma config, removing cache didn’t solve anything.

I created a new user to rule out local settings issue but I faced exactly the same issue which would indicate missing packages but I have plasma-meta package installed along with a few kde-applications including the ones mentioned in Arch wiki

pacman -Qs thumb
local/ffmpegthumbs 25.12.3-1 (kde-applications kde-multimedia)
    FFmpeg-based thumbnail creator for video files
local/kdegraphics-thumbnailers 25.12.3-1 (kde-applications kde-graphics)
    Thumbnailers for various graphics file formats

I’m using Arch with the latest plasma, AMD card, wayland session, etx4 fs, all directories are located under my home directory. I didnt’ find anything interesting in the journal.

I will be grateful for any tips.

[Krovikan]

Not the same, but in Arch too (in Ubuntu and openSUSE works) this seems related:

Icons-only taskbar doesn't show small previews no matter if the setting is toggled?

Hello, I recently installed KDE for my Arch installation and realized that the taskbar doesn’t seem to be showing the small previews for tasks when hovering over them. It works fine on my Ubuntu installation and it seems to just ignore the setting when I turn it on and off again, so I’m not sure what’s going on… [ezgif-29088a1609da9b8b]

Regards

[Daedalus]

Thx for the suggestion. In my case previews of working programs are working fine. But I did follow the link you provided and I realized that the desktop icons is actually a widget.

So:

QT_LOGGING_RULES="qml.debug=true" plasmawindowed org.kde.plasma.icontasks

gave me the this output still, doesnt look like something groundbreaking

qt.qml.propertyCache.append: Member enabled of the object DeclarativeDropArea overrides a member of the base object. Consider renaming it or adding final or over
ride specifier
qt.qml.propertyCache.append: Member visible of the object PlasmaQuick::Dialog overrides a member of the base object. Consider renaming it or adding final or over
ride specifier
file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/ui/main.qml:63: TypeError: Property ‘isScreenUiReady’ of object PlasmaWindowedCorona(0x55f
2d55e5bf0) is not a function
file:///usr/share/plasma/plasmoids/org.kde.desktopcontainment/contents/ui/main.qml:63: TypeError: Property ‘isScreenUiReady’ of object PlasmaWindowedCorona(0x55f
2d55e5bf0) is not a function
qml: 0
qml: undefined

[Krovikan]

I remember this as a very old problem that happened in KDE (it wasn’t Plasma yet). Have you tried this preference like this?:

BTW, I see .jpg files without having to have the box checked.

Regards

[skyfishgoo]

first thing i would try is to delete ~/.cache and reboot.

[Daedalus]

I have all the options enabled

[Daedalus]

I tried that too including creating a fresh new user. The behavior for old and new user.

[M.Karrde]

@Daedalus

issue which would indicate missing packages

Could totally be the issue as I had to install several additional KDE packages, not included in the Arch meta package, over time. Unfortunately can’t recall one as preview related, though.
A pacman -Qs thumb does only show fmpegthumbs (26.04.0-1 as updated yesterday) for me, the other one is not even installed and thumbnails previews are working here (as well as taskbar previews).

If you hover with the mouse in the Dolphin settings over the type a popup showing what thumbnail plugin is used (or it is trying to use) should appear, maybe that can give a hint?

For JPEG I have 2 (or 3) different ones to choose from.

[Daedalus]

I have 3 of them too:

They are pointing to: /usr/share/thumbnailers and /usr/lib/qt6/plugins/kf6/thumbcreator
I checked with ldd and all libraries seem to be in place.

[Krovikan]

In my Dolphin, I have:

and

In my software manager I found glycin:

List of packages with thumbcreator:

and with thumbnailers:

I think that you need the glycin packages.

BTW, my distro is openSUSE TW.

Regards

[Daedalus]

Thank you. I believe most of the packages you’ve listed are present in my Arch.

I wish I knew how to debug it, plasma internals look quite complex.

pacman -Qs 'glycin|ffmpegthum|thumb|kio|plasma-workspace' 

**local/ffmpegthumbs 26.04.0-1** **(kde-applications kde-multimedia)** 
    FFmpeg-based thumbnail creator for video files 
**local/glycin 2.1.1-1** 
    Sandboxed and extendable image decoding 
**local/kdegraphics-thumbnailers 26.04.0-1** **(kde-applications kde-graphics)** 
    Thumbnailers for various graphics file formats 
**local/kio 6.25.0-1** **(kf6)** 
    Resource and network access abstraction 
**local/kio-admin 26.04.0-1** **(kde-applications kde-system)** 
    Manage files as administrator using the admin:// KIO protocol 
**local/kio-extras 26.04.0-1** **(kde-applications kde-network)** 
    Additional components to increase the functionality of KIO 
**local/kio-fuse 5.1.1-1** 
    FUSE interface for KIO 
**local/plasma-workspace 6.6.4-1** **(plasma)** 
    KDE Plasma Workspace 
**local/plasma-workspace-wallpapers 6.6.4-1** **(plasma)** 
    Additional wallpapers for the Plasma Workspace

[Daedalus]

Ok I made a small discovery:

Navigating Dolphin to a system directory with wallpapers works fine, I can see all thumbnails:

Hmmm my home directory is just another partition on the same disk

[Daedalus]

SOLVED!!!

So, checking system directory (root partition) was a good idea.

The issue was related to my mounting options in fstab which were generated years ago by arch script genfstab:

This is was I had in /etc/fstab for mounting home partition:

UUID=long-uuid-number /home ext4 noauto,x-systemd.automount,rw,relatime,data=ordered 0 2

Changing it back to default:
UUID=long-uuid-number /home ext4 defaults 0 2

returned all the thumbnails and correct behavior. I guess it’s a bug either in genfstab or plasma or both. I need to do some reading on fstab flags.

[akselmo]

Can you turn this into a bug report so its documented there? Thanks!

[M.Karrde]

I have
UUID=long-uuid-number /home ext4 rw,relatime 0 2
here (as even “/” uses “… rw,relatime 0 1”)
But did not use Archinstall to setup my /home partition. In my initial setup /home was on the same (“/”) partition, I moved that to another drive later and added it to fstab manually.

[Daedalus]

Yes of course, 519142

519142 – Plasma doesn't display file thumbnails if home fs is mounted with...