Comment 0 for bug 1835671

I just ran into the same problem Amy posted, before I found this thread, I'm not sure it's the software problem or just my own hardware/system/configuration-specific problem.

But now I'm much sure it may be a general hplip software problem need to be fixed by professionals.

Just like Amy posted, I also have a Raspberry Pi Zero running Raspbian Stretch, use it as a print server, everything works fine, until one day I want it to become a scan server, so I don't have to grab an laptop and plug the usb in every time to scan some image, finally found out the scan function is totally broken on this platform.

I installed HPLIP 3.18.4 correctly, with the HP-plugin installed correctly, hp-setup with no problem, hp-check with no error.

With "scanimage -L",
I get this: device `hpaio:/usb/HP_LaserJet_MFP_M129-M134?serial=VNFYG00134' is a Hewlett-Packard HP_LaserJet_MFP_M129-M134 all-in-one

It means this rubbish machine is recognized successfully by SANE, the hpaio backend is ready, and the scanner should work with no problem.

But with "scanimage -T", or an actual scan command,
I get this: scanimage: open of device hpaio:/usb/HP_LaserJet_MFP_M129-M134?serial=VNFYG00134 failed: Error during device I/O

Check the system log, it says this:
Jul 7 17:20:49 raspberrypi scanimage: io/hpmud/musb.c 427: Found interface conf=0, iface=0, altset=0, index=1
Jul 7 17:20:49 raspberrypi scanimage: io/hpmud/musb.c 389: Active kernel driver on interface=0 ret=0
Jul 7 17:20:49 raspberrypi scanimage: io/hpmud/musb.c 535: claimed 7/1/2 interface
Jul 7 17:20:49 raspberrypi scanimage: io/hpmud/musb.c 781: read actual device_id successfully fd=1 len=277
Jul 7 17:20:50 raspberrypi scanimage: io/hpmud/musb.c 561: released 7/1/2 interface
Jul 7 17:20:50 raspberrypi scanimage: io/hpmud/hpmud.c 683: invalid channel_open state
Jul 7 17:20:50 raspberrypi scanimage: http.c 300: unable to open HP-SOAP-SCAN channel
Jul 7 17:20:50 raspberrypi scanimage: bb_soapht.c 661: unable to open http connection hp:/usb/HP_LaserJet_MFP_M129-M134?serial=VNFYG00134
Jul 7 17:20:50 raspberrypi scanimage: bb_soapht.c 793: unable to get_scanner_elements: uri=hp:/usb/HP_LaserJet_MFP_M129-M134?serial=VNFYG00134

So it's exactly the same problem Amy posted half a year ago.
It seems some "channel" should be opened but unfortunately it's not, so further communication cannot be established, and this causes an I/O error.

And it looks like this is a platform specific problem, because after all the searching, there's almost no similar report on other platforms.

Hope you pro guys can get it fixed.

Regards,
Lin