Summary: PCManFM/pcmanfm-pi shows no image thumbnails on fresh Raspberry Pi OS (Trixie) for Pi 5 installs (Imager images; “normal” and “full”). Bookworm works.
Problem
On Raspberry Pi OS, the default file manager / desktop component (PCManFM / pcmanfm-pi) does not generate or display thumbnails for common image files (PNG/JPG/WebP). Instead of thumbnails, only generic “image” icons are shown, even for files well below the configured size limit.
This is reproducible on fresh installs flashed with Raspberry Pi Imager using the official Raspberry Pi OS (Trixie) images, tested with both the “normal” and the “full” variant.
What I expected
Opening a folder with images (e.g., ~/Pictures) in PCManFM should show thumbnail previews for image/png, image/jpeg, etc., as expected on typical LXDE-based setups.
What I tested / verified
1) Basic PCManFM thumbnail settings
Verified thumbnail-related settings in libfm config:
show_thumbnail=1
thumbnail_max set high enough (tested values such as 20480 KB and 102400 KB)
“local-only thumbnails” toggled as appropriate
Cleared and recreated the thumbnail cache:
removed ~/.cache/thumbnails and recreated it
Restarted PCManFM processes and retested
Result: No thumbnails appear in PCManFM.
2) MIME associations are correct
Verified the system recognizes the files as images:
gio mime image/png
gio mime image/jpeg
Default image viewers are present (e.g., Eye of MATE / eom)
Result: MIME database/associations look fine.
3) Thumbnail infrastructure is present and works
tumbler is installed (e.g., tumbler, tumbler-common, tumbler-plugins-extra)
Started the service successfully:
systemctl --user start tumblerd → active/running
Verified the D-Bus thumbnailer service responds:
gdbus … org.freedesktop.thumbnails.Thumbnailer1 … Ping works
Verified thumbnails can be generated manually via D-Bus:
gdbus … Thumbnailer1.Queue … creates thumbnails under:
~/.cache/thumbnails/normal/
Result: The system can generate thumbnails (tumbler works), but PCManFM does not request them.
4) PCManFM does not send thumbnail requests (neither D-Bus nor external tools)
Ran dbus-monitor for org.freedesktop.thumbnails.Thumbnailer1 while opening folders in PCManFM:
No Queue / Started / Ready events triggered by PCManFM
Attached strace to the running pcmanfm --desktop process and filtered for execve:
No external thumbnailers executed (no gdk-pixbuf-thumbnailer, no ffmpegthumbnailer, etc.)
PCManFM sometimes prints warnings like:
“Could not load a pixbuf from icon theme. This may indicate that pixbuf loaders or the mime database could not be found.” Even after recreating the pixbuf loader cache, thumbnails still did not appear.
Result: PCManFM simply doesn’t trigger thumbnail generation at all.
5) Reproduced on a second fresh install
I repeated the test on another freshly flashed SD card using Raspberry Pi Imager and the official Raspberry Pi OS (Trixie) image, and saw the same behavior.
Result: This looks reproducible and not caused by a broken local configuration.
Conclusion
MIME types and thumbnail infrastructure are working.
Manual thumbnail generation via tumbler works and produces cached thumbnails.
PCManFM/pcmanfm-pi does not request thumbnails (no D-Bus requests and no external thumbnailer calls), so thumbnails never appear.
The issue reproduces across fresh installs of Raspberry Pi OS (Trixie) images.
Questions
A) Is this a known issue/regression in the current Raspberry Pi OS (Trixie) desktop packages / PCManFM build?
B) Is there a missing package/module required for PCManFM thumbnail integration?
C) Is there a recommended workaround that keeps the standard Raspberry Pi OS desktop but restores thumbnails (without switching desktop environments)?
I’m currently downgrading to Bookworm, where thumbnails work as expected.
PS: used ChatGPT/Gemini for Help and creating this Post for me
Problem
On Raspberry Pi OS, the default file manager / desktop component (PCManFM / pcmanfm-pi) does not generate or display thumbnails for common image files (PNG/JPG/WebP). Instead of thumbnails, only generic “image” icons are shown, even for files well below the configured size limit.
This is reproducible on fresh installs flashed with Raspberry Pi Imager using the official Raspberry Pi OS (Trixie) images, tested with both the “normal” and the “full” variant.
What I expected
Opening a folder with images (e.g., ~/Pictures) in PCManFM should show thumbnail previews for image/png, image/jpeg, etc., as expected on typical LXDE-based setups.
What I tested / verified
1) Basic PCManFM thumbnail settings
Verified thumbnail-related settings in libfm config:
show_thumbnail=1
thumbnail_max set high enough (tested values such as 20480 KB and 102400 KB)
“local-only thumbnails” toggled as appropriate
Cleared and recreated the thumbnail cache:
removed ~/.cache/thumbnails and recreated it
Restarted PCManFM processes and retested
Result: No thumbnails appear in PCManFM.
2) MIME associations are correct
Verified the system recognizes the files as images:
gio mime image/png
gio mime image/jpeg
Default image viewers are present (e.g., Eye of MATE / eom)
Result: MIME database/associations look fine.
3) Thumbnail infrastructure is present and works
tumbler is installed (e.g., tumbler, tumbler-common, tumbler-plugins-extra)
Started the service successfully:
systemctl --user start tumblerd → active/running
Verified the D-Bus thumbnailer service responds:
gdbus … org.freedesktop.thumbnails.Thumbnailer1 … Ping works
Verified thumbnails can be generated manually via D-Bus:
gdbus … Thumbnailer1.Queue … creates thumbnails under:
~/.cache/thumbnails/normal/
Result: The system can generate thumbnails (tumbler works), but PCManFM does not request them.
4) PCManFM does not send thumbnail requests (neither D-Bus nor external tools)
Ran dbus-monitor for org.freedesktop.thumbnails.Thumbnailer1 while opening folders in PCManFM:
No Queue / Started / Ready events triggered by PCManFM
Attached strace to the running pcmanfm --desktop process and filtered for execve:
No external thumbnailers executed (no gdk-pixbuf-thumbnailer, no ffmpegthumbnailer, etc.)
PCManFM sometimes prints warnings like:
“Could not load a pixbuf from icon theme. This may indicate that pixbuf loaders or the mime database could not be found.” Even after recreating the pixbuf loader cache, thumbnails still did not appear.
Result: PCManFM simply doesn’t trigger thumbnail generation at all.
5) Reproduced on a second fresh install
I repeated the test on another freshly flashed SD card using Raspberry Pi Imager and the official Raspberry Pi OS (Trixie) image, and saw the same behavior.
Result: This looks reproducible and not caused by a broken local configuration.
Conclusion
MIME types and thumbnail infrastructure are working.
Manual thumbnail generation via tumbler works and produces cached thumbnails.
PCManFM/pcmanfm-pi does not request thumbnails (no D-Bus requests and no external thumbnailer calls), so thumbnails never appear.
The issue reproduces across fresh installs of Raspberry Pi OS (Trixie) images.
Questions
A) Is this a known issue/regression in the current Raspberry Pi OS (Trixie) desktop packages / PCManFM build?
B) Is there a missing package/module required for PCManFM thumbnail integration?
C) Is there a recommended workaround that keeps the standard Raspberry Pi OS desktop but restores thumbnails (without switching desktop environments)?
I’m currently downgrading to Bookworm, where thumbnails work as expected.
PS: used ChatGPT/Gemini for Help and creating this Post for me
Statistics: Posted by Craser — Sun Feb 08, 2026 2:30 pm