Scanner not detected if plugged once Kubuntu 18.04 is running

[Victor Marin]

In Kubuntu 16.04 the scanners were detected by Xsane or other scan programs as soon as it were plugged in. Also, if you unplugged it then plugged in again also Xsane detected it immediately.

But in Kubuntu 18.04 the scanner is not detected by Xsane if you plug in once Kubuntu 18.04 already running. Only it's detected if you starts session with the scanner already plugged in. And if you unplugg it then plug it again it is not detected anymore and you must restart the computer with the cable plugged into the USB, to be detected.

It happens the same thing with other scan programs like Skanlite or Simple Scan.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: usbutils 1:007-4build1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: KDE
Date: Wed May 16 10:25:29 2018
InstallationDate: Installed on 2018-05-07 (8 days ago)
InstallationMedia: Kubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
SourcePackage: usbutils
UpgradeStatus: No upgrade log present (probably fresh install)

[Victor Marin (vic64)]

Also, I just confirmed that although Xsane and other scan programs like Simple Scan and Skanlite detect the scanner (only if it is already plugged in when Kubuntu 18.04 starts), however only Xsane works Ok (except that in this 18.04 version of Kubuntu Xsane program only starts receiving data once the exploration of the document has finished, which makes much slower scanning several documents, as I describe in the Bug #1771520.

Simple Scan and Skanlite detects the EPSON Perfection V39 scanner (if already plugged before starting Kubuntu 18.04 as above said) but don't start scanning.

[Victor Marin (vic64)]

Just found the solution for this bug, in https://forums.linuxmint.com/viewtopic.php?t=221071

It's that xsltproc has to be installed.

Once I did it and restarted, now Xsane detects the scanner also when I unplug and then plug again the usb cable, that's to say now it has the plug & play or hot-plug capability. And works Ok.

Simple Scan and Skanlite detects the EPSON Perfection V39 scanner (now also with the hot-plug capability) but don't start scanning yet.