I have a Panasonic KX-MB 1500 multifunction laser printer/scanner. This worked perfectly until Ubuntu 16.04. Since then (including on 19.04) only the printer works, not the scanner.
Panasonic provides drivers for Ubuntu & Redhat here: http://panasonic.net/pcc/support/fax/common/table/linuxdriver.html
Upon installing the scanner driver, no front-end can see the scanner. Here is the output of lsusb & sane-find-scanner. Running sane-find-scanner or scanImage -L as sudo does not make any difference.
$ lsusb Bus 002 Device 002: ID 8087:8000 Intel Corp. Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 8087:8008 Intel Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 003: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader Bus 003 Device 002: ID 0461:4e22 Primax Electronics, Ltd **Bus 003 Device 006: ID 04da:0f0b Panasonic (Matsushita)** Bus 003 Device 004: ID 04d9:1203 Holtek Semiconductor, Inc. Keyboard Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
$ sudo sane-find-scanner # sane-find-scanner will now attempt to detect your scanner. If the # result is different from what you expected, first make sure your # scanner is powered up and properly connected to your computer. # No SCSI scanners found. If you expected something different, make sure that # you have loaded a kernel SCSI driver for your SCSI adapter. could not fetch string descriptor: Input/output error could not fetch string descriptor: Pipe error could not fetch string descriptor: Pipe error # No USB scanners found. If you expected something different, make sure that # you have loaded a kernel driver for your USB host controller and have setup # the USB system correctly. See man sane-usb for details. # Not checking for parallel port scanners. # Most Scanners connected to the parallel port or other proprietary ports # can't be detected by this program.