symbol lookup error: /usr/lib/x86_64-linux-gnu/libgusb.so.2: undefined symbol: libusb_has_capability

How is the message shown? On the command line?
Can you attach the file ~/.cache/simple-scan/simple-scan.log after this occurs? (Or run simple-scan -d from the command line)
Do you have any SANE drivers installed? You can see them in /usr/lib/sane

My guess at the problem is either you have something incorrectly installed or you have a SANE driver that has a mismatch with your installed version of libgusb.

I am having the same issue,

Nothing is written in the ~/.cache/simple-scan/simple-scan.log file.

Running simple-scan -d prints this to shell
[+0.00s] DEBUG: simple-scan.vala:674: Starting Simple Scan 3.18.1, PID=14680
[+0.01s] DEBUG: Connecting to session manager
[+0.07s] DEBUG: ui.vala:2018: Loading state from /home/****/.cache/simple-scan/state
[+0.07s] DEBUG: ui.vala:1986: Restoring window to 600x400 pixels
[+0.07s] DEBUG: autosave-manager.vala:64: Loading autosave information
[+0.07s] DEBUG: autosave-manager.vala:259: Waiting to autosave...
simple-scan: symbol lookup error: /usr/lib/x86_64-linux-gnu/libgusb.so.2: undefined symbol: libusb_has_capability

Nothing in /usr/lib/sane. The directory doesn't even exist.

I had the same problem as the reporter. It turns out I had a libusb file in my /usr/local/lib:

jrivera@bohr:~/work$ ldd `which simple-scan` | grep usb
 libgusb.so.2 => /usr/lib/x86_64-linux-gnu/libgusb.so.2 (0x00007fcb64e3a000)
 libusb-1.0.so.0 => /usr/local/lib/libusb-1.0.so.0 (0x00007fcb5eefb000)

which turned out to be a symlink to a Microchip customized version of libusb for using with the MPLABX software. It is probably an outdated version of libusb that has no libusb_has_capability:

jrivera@bohr:~$ file /usr/local/lib/libusb-1.0.so.0
/usr/local/lib/libusb-1.0.so.0: symbolic link to libmchpusb-1.0.so
jrivera@bohr:~$ file /usr/local/lib/libmchpusb-1.0.so
/usr/local/lib/libmchpusb-1.0.so: symbolic link to /opt/microchip/mplabcomm1.0/libusb-1.0.so.0.0.0
jrivera@bohr:~$ file /opt/microchip/mplabcomm1.0/libusb-1.0.so.0.0.0
/opt/microchip/mplabcomm1.0/libusb-1.0.so.0.0.0: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=5323c4498c0b9d123a751dccb8c4a4b52aa6bc83, not stripped

According to this thread: http://www.microchip.com/forums/m729021.aspx ldconfig restores the link even after removing.

This could be the orginal poster's (and MIna Shokry's) problem, or something similar happening. I would suggest them to run ldd `which simple-scan` and post the output to help them further.

[Expired for Simple Scan because there has been no activity for 60 days.]

After removing MPLAB X software and deleting link /usr/local/lib/libusb-1.0.so.0 Simple Scan is running fine.