Bug 510598

Thanks for the report!

Can you give a bit more details? 
What version are you using?
What scanner are you using?
Are you trying to save locally or remote?

Can you start skanlite in a terminal and attach the output here? (preferably with the debug environment variable set for your scanner-back-end)
Something like:
SANE_DEBUG_<Some backend>=16 skanlite

Skanlite version is 23.08.5
The scanner is a Brother DCP-585 CW
I'm under Kubuntu 24.04, Linux 6.8.0-85-generic, but I remember it also happened with previous versions (22.04)

Sorry I don't understand what I'm supposed to do with the environment variable ?

Let's make sure we know the driver. So in a terminal execute:

scanimage -L

and copy and paste the output here. Then we can continue with the skanlite command. I suspect that it could be something like:

SANE_DEBUG_BROTHER3=16 skanlite
or
SANE_DEBUG_BRSCAN=16 skanlite

But I don't know for sure until I have seen the output from scanimage -L (might not after that either)

Your version of skanlite is already quite old, so there is a chance that the scanning would work as expected in a newer version of Kubuntu

In a terminal, when I run the command skanlite :
when I get the view of the the document I just scanned, as soon as I click the "save" button, these lines appears in the bash :

kf.kio.filewidgets.kfilefiltercombo: Could not find filter "image/png"
kf.kio.filewidgets.kfilefiltercombo: Could not find filter "*.png|image PNG "
kf.kio.widgets.kdirmodel: No node found for item that was just removed: QUrl("file:///home/[my name]/signal-desktop-keyring.gpg")

Then, whether I save abort, skanlite won't scan anymore until I restart it.

scanimage -L gets me :
device `brother3:net1;dev0' is a Brother DCP-585CW DCP-585CW


SANE_DEBUG_BROTHER3=16 skanlite gets me :
[10:40:56.248584] [sanei_debug] Setting debug level of brother3 to 16.
[10:40:56.248614] [brother3] brother init
[10:40:56.248639] [brother3] brother version: 1000001
[10:40:56.574504] [brother3] starting bus scan
[10:40:56.574548] [brother3] scanning bus 004
[10:40:56.574560] [brother3] found dev 1D6B/0003
[10:40:56.574575] [brother3] scanning bus 003
[10:40:56.574588] [brother3] found dev 8087/0026
[10:40:56.574603] [brother3] found dev 30C9/0010
[10:40:56.574616] [brother3] found dev 1D6B/0002
[10:40:56.574630] [brother3] scanning bus 002
[10:40:56.574646] [brother3] found dev 1D6B/0003
[10:40:56.574662] [brother3] scanning bus 001
[10:40:56.574676] [brother3] found dev 1D6B/0002
kf.kio.filewidgets.kfilefiltercombo: Could not find filter "image/png"
kf.kio.filewidgets.kfilefiltercombo: Could not find filter "*.png|image PNG "
kf.kio.widgets.kdirmodel: No node found for item that was just removed: QUrl("file:///home/[my name]/signal-desktop-keyring.gpg")
[10:41:25.610520] [brother3] cancel called...
[10:42:06.541143] [brother3] cancel called...
[10:44:01.500760] [brother3] cancel called...
[10:44:26.732916] [brother3] cancel called...
[10:44:33.239297] [brother3] cancel called...

(a new line with "[brother3] cancel called..." appear each time the "Error during device I/O" error box pops, and each time I acknowledge it.

Is there a way to get a newer version of Skanlite without upgrading the OS ?
I'm used to wait for the LTS versions.

Hmm...

Can you try to increase the debug level to 128?

Updating the application without updating the distro is a bit complicated... :(

If you don't have anything against Snaps or Flatpack, you can try those, but they can have problems with proprietary drivers
https://snapcraft.io/skanpage
 (Skanpage not Skanlite but same family ;) I could not find Skanlite )
https://flathub.org/en/apps/org.kde.skanlite
https://flathub.org/en/apps/org.kde.skanpage