Bug 453553

Summary:	Dolphin not caching thumbnails
Product:	[Frameworks and Libraries] kio-extras	Reporter:	David Karlsson <davikar80>
Component:	Thumbnails and previews	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	REPORTED ---
Severity:	normal	CC:	davikar80, nicolas.fella, pouchoflavender
Priority:	NOR
Version First Reported In:	22.04.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Microsoft Windows
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description David Karlsson 2022-05-08 19:20:32 UTC

SUMMARY
 I am using Dolphin under WSLg (with Windows 11) and have a filesystem mounted with drvfs (9p).
And while Dolphin is generating the video thumbnails as it should, none of them are cached under ~/.cache/thumbnails.
Caching is working as normal on the root filesystem.
(I'm assuming this is handled by ffmpegthumbs, but it could be Dolphin too).

Fully updated Arch, with KDE Plasma 5.24.5 and KDE Gear 22.04 running under WSLg.

STEPS TO REPRODUCE
1.  Mount filesystem with drvfs.
2. Browse filesystem with Dolphin.
3. Find video files and wait for thumbnails to generate.
4. Look for cached thumbnails under ~/.cache/thumbnails/.

OBSERVED RESULT
~/.cache/thumbnails/ is empty except for folders like normal, large, x-large. (Assuming it was emptied before browsing).

EXPECTED RESULT
There should be cached thumbnails in the folders.

SOFTWARE/OS VERSIONS
Windows:  Windows 11 with WSL/WSLg
Linux/KDE Plasma:  Arch Linux
KDE Plasma Version:  5.24.5
KDE Frameworks Version:  5.93.0
Qt Version: idk, the latest one

ADDITIONAL INFORMATION

Comment 1 pouchoflavender 2025-12-14 16:25:41 UTC

For me, Dolphin doesn't save any thumbnails to the cache, regenerating them each time.
My home and root directories are distinct subvolumes of the same btrfs partition, while ~/.cache is mounted on a different physical drive (also formatted with btrfs).
The Thunar file manager, on the other hand, seems to be able to save file thumbnails to ~/.cache/thumbnails just fine, as well as being able to reuse them. So it's not a problem with file system access.

Linux/KDE Plasma: Debian GNU/Linux testing (forky)
KDE Plasma Version: 6.5.3
KDE Frameworks Version: 6.20.0
Qt Version: 6.9.2