Bug 513562

Summary: Thumnails of PDF files
Product: [Applications] dolphin Reporter: Ryusanz <ryuji>
Component: generalAssignee: Dolphin Bug Assignee <dolphin-bugs-null>
Status: REPORTED ---    
Severity: normal CC: dolphin-bugs-null, nicolas.fella
Priority: NOR    
Version First Reported In: 25.11.80   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Ryusanz 2025-12-19 05:25:47 UTC 
đź”´ Bug report draft (ready to submit)

Product: Dolphin
Component: General / Thumbnails
Version: Dolphin (Plasma 6, Qt6)
Severity: normal
Platform: Linux
OS: Kubuntu 25.10 (Plasma 6)

Summary

Dolphin endlessly spawns Ghostscript and fails to generate PDF thumbnails on external mounts (/mnt), while image thumbnails work

Description

On Kubuntu 25.10 (Plasma 6), Dolphin fails to generate PDF thumbnails for files located on an external hard drive mounted under /mnt/....

Image thumbnails (JPG/PNG) work correctly on the same mount.
PDF thumbnails are generated correctly by GNOME Files (Nautilus), and once generated there, Dolphin can display them from the shared thumbnail cache.

However, when Dolphin attempts to generate PDF thumbnails by itself, it repeatedly spawns Ghostscript, which immediately exits with an unrecoverable error. This results in an infinite loop of failed attempts and continuous log spam.

Steps to Reproduce

Mount an external drive via /etc/fstab under /mnt/...

Place PDF files on that drive

Open the directory in Dolphin

Enable thumbnail previews for PDF/PostScript in Dolphin settings

Expected Result

PDF thumbnails should be generated once and displayed normally

Dolphin should stop retrying on failure

Actual Result

No PDF thumbnails are generated

Dolphin repeatedly spawns Ghostscript processes

journalctl --user -f shows endless errors like:

dolphin[PID]: GPL Ghostscript 10.05.0: Unrecoverable error, exit code 1


CPU usage and logs increase continuously until the view is closed

Additional Observations

JPG/PNG thumbnails work correctly on the same mount

The same PDF files generate thumbnails correctly in GNOME Files (Nautilus)

Once GNOME generates the thumbnails, Dolphin can display them (shared ~/.cache/thumbnails)

Disabling PDF previews in Dolphin immediately stops the errors

Running Dolphin with GS_OPTIONS=-dNOSAFER does not change the behavior

strace -f -e execve dolphin does not show Ghostscript being execve’d, despite the repeated errors logged by Dolphin

Logs

From journalctl --user -f while opening a directory with PDFs:

dolphin[40424]: GPL Ghostscript 10.05.0: Unrecoverable error, exit code 1
dolphin[40425]: GPL Ghostscript 10.05.0: Unrecoverable error, exit code 1
dolphin[40426]: GPL Ghostscript 10.05.0: Unrecoverable error, exit code 1
...
(repeats indefinitely)

Environment

Kubuntu 25.10

Plasma 6

Dolphin (Qt6 / KF6)

Ghostscript 10.05.0

External HDD mounted via /etc/fstab under /mnt/...

Filesystem: (fill in if desired, e.g. ext4)

Workaround

Disable “PDF / PostScript” previews in Dolphin

Or generate thumbnails once via GNOME Files

Notes

This appears to be a regression or error-handling bug in Dolphin’s PDF thumbnail generation path (Ghostscript invocation). Dolphin does not stop retrying after repeated failures.
Comment 1 Nicolas Fella 2025-12-19 09:42:49 UTC 
Please do not submit AI-generated bugreports, thanks.
Comment 2 Ryusanz 2025-12-19 10:19:09 UTC 
Understood, sorry about that.

The issue itself is real and fully reproducible on my system.
I personally observed and verified all described behavior:
- PDF thumbnails fail only in Dolphin
- JPG thumbnails work on the same mount
- Endless Ghostscript errors occur
- GNOME Files generates the thumbnails correctly
- Disabling PDF previews stops the errors

I used AI only to help organize the English text, not to invent the issue.
If you prefer, I can restate the problem briefly in my own words or 
provide additional logs/tests.

Thanks for your time.

Ryuji Otsuka from Roppongi, Tokyo, Japan

On 2025/12/19 18:42, Nicolas Fella wrote:
> https://bugs.kde.org/show_bug.cgi?id=513562
>
> Nicolas Fella <nicolas.fella@gmx.de> changed:
>
>             What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                   CC|                            |nicolas.fella@gmx.de
>
> --- Comment #1 from Nicolas Fella <nicolas.fella@gmx.de> ---
> Please do not submit AI-generated bugreports, thanks.
>
Comment 3 Ryusanz 2025-12-19 10:22:04 UTC 
Understood, sorry about that.

The issue itself is real and fully reproducible on my system.
I personally observed and verified all described behavior:
- PDF thumbnails fail only in Dolphin
- JPG thumbnails work on the same mount
- Endless Ghostscript errors occur
- GNOME Files generates the thumbnails correctly
- Disabling PDF previews stops the errors

I used AI only to help organize the English text, not to invent the issue.
If you prefer, I can restate the problem briefly in my own words or provide additional logs/tests.

Thanks for your time.

Ryuji Otsuka from Roppongi, Tokyo, Japan

On 2025/12/19 18:42, Nicolas Fella wrote:
> https://bugs.kde.org/show_bug.cgi?id=513562
>
> Nicolas Fella <nicolas.fella@gmx.de> changed:
>
>             What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                   CC|                            |nicolas.fella@gmx.de
>
> --- Comment #1 from Nicolas Fella <nicolas.fella@gmx.de> ---
> Please do not submit AI-generated bugreports, thanks.
Comment 4 Ryusanz 2025-12-24 08:03:56 UTC 
I tested Ghostscript directly and it fails outside Dolphin.

gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -sOutputFile=/tmp/test.png AC.pdf

Result:
Error: /undefinedfilename in (AC.pdf)
Last OS error: Permission denied
GPL Ghostscript 10.05.0: Unrecoverable error, exit code 1

The PDF is located on /mnt/Data (ext4, rw,noatime).
JPG thumbnails work.
Nautilus can generate PDF thumbnails (poppler-based), Dolphin cannot.

So this seems to be a Ghostscript SAFER restriction causing Dolphin to retry endlessly.