Bug 501882 - SMB shares no longer show folder previews
Summary: SMB shares no longer show folder previews
Status: RESOLVED FIXED
Alias: None
Product: frameworks-kio
Classification: Frameworks and Libraries
Component: general (other bugs)
Version First Reported In: 6.12.0
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: KIO Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-03-22 20:13 UTC by Patrick Gianelli
Modified: 2025-09-24 08:39 UTC (History)
6 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


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Description Patrick Gianelli 2025-03-22 20:13:50 UTC
SUMMARY
Prior too 6.12, folder previews displayed normally for SMB shares. Updating to 6.12, previews do not show. NFS shares continue to function normally.

STEPS TO REPRODUCE
1. Check "show previews for folders" in settings in Dolphin
2. Set file preview size to some large number (1GB)
3. Mount a SMB share, eg: sudo mount -t cifs -o credentials=/home/user/.creds,uid=user,exec,mfsymlinks //192.168.1.10/Share /mnt/Share/
4. Create a folder.
5. Put photos in the folder

OBSERVED RESULT
Folder shows with no previews on it. File thumbnails function normally.

NFS shares continue to work normally.

EXPECTED RESULT
Folder previews work.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch, 6.13.7
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION
Comment 1 flan_suse 2025-04-02 02:30:31 UTC
Confirmed. I noticed this bug after I updated.

Operating System: Manjaro Linux 
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Dolphin Version: 24.12.3
Qt Version: 6.8.2
Kernel Version: 6.12.19-1-MANJARO (64-bit)
Graphics Platform: X11
Graphics Processor: Intel® Iris® Xe Graphics
Comment 2 flan_suse 2025-05-11 22:57:25 UTC
Does anyone know which commit introduced this bug in Dolphin?

Using Dolphin on my network shares is almost unusable now. :(
Comment 3 flan_suse 2025-05-20 23:09:30 UTC Comment hidden (spam)
Comment 4 flan_suse 2025-06-09 15:03:15 UTC Comment hidden (spam)
Comment 5 flan_suse 2025-08-05 22:12:10 UTC
This problem seems to be deeper than Dolphin. It also affects other Qt-based file managers like PCManFM-Qt.
Comment 6 flan_suse 2025-08-17 14:36:03 UTC
This bug report seems to have found the culprit of why folder previews are not being generated. It also affects bcachefs, not just SMB.

The fix is extremely simple, as explained in the first comment of the other bug report.

https://bugs.kde.org/show_bug.cgi?id=507488
Comment 7 kde.b341l 2025-08-17 23:18:51 UTC
(In reply to flan_suse from comment #6)
> This bug report seems to have found the culprit of why folder previews are
> not being generated. It also affects bcachefs, not just SMB.
> 
> The fix is extremely simple, as explained in the first comment of the other
> bug report.
> 
> https://bugs.kde.org/show_bug.cgi?id=507488

Forgive my lack of knowledge, but when you say "the fix is extremely simple", which part are you referring to.
I'm guessing it's this: "Commenting out the above size check restores the folder thumbnails."
If so, what would a simpleton like me need to do to achieve this? Recompile "Kio" with the size-check commented out? Or something simpler?
Comment 8 flan_suse 2025-08-18 01:00:19 UTC
(In reply to kde.b341l from comment #7)
> If so, what would a simpleton like me need to do to achieve this? Recompile
> "Kio" with the size-check commented out? Or something simpler?

That's what the other user did. Either that or wait for the devs to reverse their mistake that was introduced in KIO frameworks 6.12.

I'm currently using a patched version of Dolphin to undo a different bug. I might have to resort to using two patched components of KDE, since these obvious bugs seem to take a while to fix. :shrug:

At the end of the day we need a usable desktop. The QoL issues really hinder workflow, since it's something you see every day doing common things on your computer.
Comment 9 flan_suse 2025-08-18 01:01:37 UTC
*** Bug 507488 has been marked as a duplicate of this bug. ***
Comment 10 kde.b341l 2025-08-18 05:29:37 UTC
> At the end of the day we need a usable desktop. The QoL issues really hinder
> workflow, since it's something you see every day doing common things on your
> computer.

Yes, it's quite annoying! 
Does the other Dolphin "bug" you mentioned happen to be the missing details/metadata on network folders? Cause that's what I'm really trying to solve.
Comment 11 Akseli Lahtinen 2025-08-28 13:49:52 UTC
Is this only for SMB connections? It works for me with sftp.

Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.80
KDE Frameworks Version: 6.18.0
Qt Version: 6.9.1
Kernel Version: 6.15.10-200.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 3600 6-Core Processor
Memory: 16 GiB of RAM (15.5 GiB usable)
Graphics Processor: AMD Radeon RX 6600
Comment 12 flan_suse 2025-08-28 23:36:02 UTC
(In reply to Akseli Lahtinen from comment #11)
> Is this only for SMB connections? It works for me with sftp.

It affects SMB and bcachefs, or anything else where "stat" reports a folder as having a "0 byte size".

It does not affect NFS, XFS, and Ext4.

See comment #6
https://bugs.kde.org/show_bug.cgi?id=501882#c6
Comment 13 Bug Janitor Service 2025-09-12 03:48:17 UTC
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!
Comment 14 flan_suse 2025-09-12 13:57:54 UTC
(In reply to Bug Janitor Service from comment #13)
> 🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15
> days. Please provide the requested information, then set the bug status to
> REPORTED. If there is no change for at least 30 days, it will be
> automatically closed as RESOLVED WORKSFORME.

Needs info? What info is needed? The bug exists, is reproducible, and was identified in the code.
Comment 15 Patrick Gianelli 2025-09-12 20:23:06 UTC
(In reply to Bug Janitor Service from comment #13)
> 🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15
> days. Please provide the requested information, then set the bug status to
> REPORTED. If there is no change for at least 30 days, it will be
> automatically closed as RESOLVED WORKSFORME.
> 
> For more information about our bug triaging procedures, please read
> https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.
> 
> Thank you for helping us make KDE software even better for everyone!

What info is needed? The bug still repros in current code and the bug, per comments here, should be understood.
Comment 16 Akseli Lahtinen 2025-09-13 17:01:20 UTC
Sorry, someone forgot to reset the status so the bot did it's thing.
Comment 17 flan_suse 2025-09-13 17:06:22 UTC
(In reply to Akseli Lahtinen from comment #16)
> Sorry, someone forgot to reset the status so the bot did it's thing.

Why did you change it from CONFIRMED back to REPORTED?

This is 100% reproducible and the regression was located in the code. There is no mystery. Fixing that one line in the code fixes this bug that didn't exist before Frameworks 6.12.0.

See comment #6
https://bugs.kde.org/show_bug.cgi?id=501882#c6
Comment 18 Akseli Lahtinen 2025-09-13 18:50:18 UTC
I have not seen another KDE developer confirm this bug, that's why it's back to reported. In case I'm wrong, feel free to change it back.
Comment 19 flan_suse 2025-09-13 21:10:07 UTC
(In reply to Akseli Lahtinen from comment #18)
> I have not seen another KDE developer confirm this bug, that's why it's back
> to reported. In case I'm wrong, feel free to change it back.

It's thoroughly explained here:
https://bugs.kde.org/show_bug.cgi?id=507488#c0

When the reporter commented out the size check for "0 byte" folders, the bug goes away.

SMB and Bcachefs happen to stat folders at exactly 0 bytes, even with files inside.

NFS, Ext4, XFS, and others do not.

So this new check in Frameworks will skip folder previews for any folder that reports "0 bytes" because it assumes the folder is empty. This is why we no longer get folder previews on SMB or Bcachefs.
Comment 20 flan_suse 2025-09-23 14:48:07 UTC
Are we waiting for a KDE dev to confirm this bug that is already reproduced and confirmed and the source of the bug was spotted in the code?

I don't understand what we're waiting for?

We need folder previews for SMB shares and Bcachefs. I can't stress enough how much this hinders my ability to use my PC. I'm having to reboot into Windows just to use my SMB shares, which have many folders, and work with photos and videos.
Comment 21 Akseli Lahtinen 2025-09-23 14:50:12 UTC
If you have a fix ready feel free to make a merge request
Comment 22 Mikhail Morozov 2025-09-23 16:47:26 UTC
Created a merge request at https://invent.kde.org/frameworks/kio/-/merge_requests/2004
Comment 23 Méven 2025-09-24 08:39:20 UTC
Git commit 8a713b01dd94027a8869b8dc417af162f61abac2 by Méven Car, on behalf of Mikhail Morozov.
Committed on 24/09/2025 at 08:39.
Pushed by meven into branch 'master'.

filepreviewjob: Don't apply size check to directories

If a folder is situated on a bcachefs partition (or any other directory with 0 sized directory entry) its icon in Dolphin will not display thumbnails of its contents regardless of the preview options.

Judging by the log line `"PreviewJob: skipping an empty file, migth be a broken symlink"`, the size check should only apply to files not folders.
Related: bug 507488

M  +2    -2    src/gui/filepreviewjob.cpp

https://invent.kde.org/frameworks/kio/-/commit/8a713b01dd94027a8869b8dc417af162f61abac2