Scan on OJPro 8730 via network crashes

[Dirk Reymann]

Short: Scaning via network from OfficeJetPro8730 fails (crashes?) while same from other OfficeJetPro works.

Details:
Lenovo Thinkpad T60p, Linux Mint 19.1 fresh install, HPLIP 3.19.3 clean install, connected to router via WiFi
HP OJPro8730 connected to router via Ethernet
HP OJPro8500 connected to router via Ethernet

Both AiO-printers detected an installed without problem.
Printing on 8500 works fine.
Printing on 8730 works fine.
Scanning on 8500 works fine.
Scanning on 8730 fails!

Using XSANE 0.999 these effects occur:
- XSANE properly finds both printers.
- XSANE opens up correctly and parameters for 8730 may be set up.
- Clicking on "Scan" starts the process...
- Scanner unit immediately lights up and starts moving as expected.
- XSANE seems not to receive any data.
- After some time XSANE exits and reports "Speicherzugriffsfehler (Speicherabzug geschrieben)" on stderr (= memory access violation ?)
- The job log on the 8730's EWS shows the scan attempt with title "HTTP" and result "aborted".

Using simple-scan the behavior is identical, except for simple-scan exiting with error "unable to start scan".

--------------------------------------------------------------

user@user-ThinkPad-T60p:~$ hp-check -t
Saving output in log file: /home/user/hp-check.log

HP Linux Imaging and Printing System (ver. 3.19.3)
Dependency/Version Check Utility ver. 15.1

Copyright (c) 2001-18 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Note: hp-check can be run in three modes:
1. Compile-time check mode (-c or --compile): Use this mode before compiling the HPLIP supplied tarball (.tar.gz or .run) to determine if the proper dependencies are
installed to successfully compile HPLIP.
2. Run-time check mode (-r or --run): Use this mode to determine if a distro supplied package (.deb, .rpm, etc) or an already built HPLIP supplied tarball has the proper
dependencies installed to successfully run.
3. Both compile- and run-time check mode (-b or --both) (Default): This mode will check both of the above cases (both compile- and run-time dependencies).

Check types:
a. EXTERNALDEP - External Dependencies
b. GENERALDEP - General Dependencies (required both at compile and run time)
c. COMPILEDEP - Compile time Dependencies
d. [All are run-time checks]
PYEXT SCANCONF QUEUES PERMISSION

Status Types:
    OK
    MISSING - Missing Dependency or Permission or Plug-in
    INCOMPAT - Incompatible dependency-version or Plugin-version

---------------
| SYSTEM INFO |
---------------

 Kernel: 4.15.0-48-generic #51-Ubuntu SMP Wed Apr 3 08:26:08 UTC 2019 GNU/Linux
 Host: user-ThinkPad-T60p
 Proc: 4.15.0-48-generic #51-Ubuntu SMP Wed Apr 3 08:26:08 UTC 2019 GNU/Linux
 Distribution: 22 19.1
 Bitness: 32 bit

-----------------------
| HPLIP CONFIGURATION |
-----------------------

HPLIP-Version: HPLIP 3.19.3
HPLIP-Home: /usr/share/hplip
HPLIP-Installation: Auto installation is supported for linuxmint distro 19.1 version

Current contents of '/etc/hp/hplip.conf' file:
# hplip.conf. Generated from hplip.conf.in by configure.

[hplip]
version=3.19.3

[dirs]
home=/usr/share/hplip
run=/var/run
ppd=/usr/share/ppd/HP
ppdbase=/usr/share/ppd
doc=/usr/share/doc/hplip-3.19.3
html=/usr/share/doc/hplip-3.19.3
icon=/usr/share/applications
cupsbackend=/usr/lib/cups/backend
cupsfilter=/usr/lib/cups/filter
drv=/usr/share/cups/drv/hp
bin=/usr/bin
apparmor=/etc/apparmor.d
# Following values are determined at configure time and cannot be changed.
[configure]
network-build=yes
libusb01-build=no
pp-build=no
gui-build=yes
scanner-build=yes
fax-build=yes
dbus-build=yes
cups11-build=no
doc-build=yes
shadow-build=no
hpijs-install=no
foomatic-drv-install=no
foomatic-ppd-install=no
foomatic-rip-hplip-install=no
hpcups-install=yes
cups-drv-install=yes
cups-ppd-install=no
internal-tag=3.19.3
restricted-build=no
ui-toolkit=qt4
qt3=no
qt4=yes
qt5=no
policy-kit=no
lite-build=no
udev_sysfs_rules=no
hpcups-only-build=no
hpijs-only-build=no
apparmor_build=yes
class-driver=no

Current contents of '/var/lib/hp/hplip.state' file:
Plugins are not installed. Could not access file: Datei oder Verzeichnis nicht gefunden

Current contents of '~/.hplip/hplip.conf' file:
[commands]
scan = /usr/bin/simple-scan %SANE_URI%

[fax]
email_address =
voice_phone =

[last_used]
device_uri = "hp:/net/Officejet_Pro_8500_A910?ip=192.168.178.24"
printer_name =
working_dir = .

[polling]
device_list =
enable = false
interval = 5

[refresh]
enable = false
rate = 30
type = 1

[settings]
systray_messages = 0
systray_visible = 1

[upgrade]
last_upgraded_time = 1556142100
notify_upgrade = true
pending_upgrade_time = 0
latest_available_version = 3.17.10

[installation]
date_time = 25.04.2019 00:50:21
version = 3.19.3

 <Package-name> <Package-Desc> <Required/Optional> <Min-Version> <Installed-Version> <Status> <Comment>

--------------
| COMPILEDEP |
--------------

 gcc gcc - GNU Project C and C++ Compiler REQUIRED - 7.3.0 OK -
 make make - GNU make utility to maintain groups of programs REQUIRED 3.0 4.1 OK -
 libtool libtool - Library building support services REQUIRED - 2.4.6 OK -

------------------------
| General Dependencies |
------------------------

 libcrypto libcrypto - OpenSSL cryptographic library REQUIRED - 1.1.0 OK -
 python-xml Python XML libraries REQUIRED - 2.2.5 OK -
 libnetsnmp-devel libnetsnmp-devel - SNMP networking library development files REQUIRED 5.0.9 5.7.3 OK -
 sane-devel SANE - Scanning library development files REQUIRED - - OK -
 pil PIL - Python Imaging Library (required for commandline scanning with hp-scan) OPTIONAL - 1.1.7 OK -
 pyqt4-dbus PyQt 4 DBus - DBus Support for PyQt4 REQUIRED 4.0 4.12.1 OK -
 libpthread libpthread - POSIX threads library REQUIRED - 2.27 OK -
 python-devel Python devel - Python development files REQUIRED 2.2 2.7.15 OK -
 cups-devel CUPS devel- Common Unix Printing System development files REQUIRED - 2.2.7 OK -
 python-dbus Python DBus - Python bindings for DBus REQUIRED 0.80.0 1.2.6 OK -
 cups-ddk CUPS DDK - CUPS driver development kit OPTIONAL - - OK -
 reportlab Reportlab - PDF library for Python OPTIONAL 2.0 3.4.0 OK -
 pyqt4 PyQt 4- Qt interface for Python (for Qt version 4.x) REQUIRED 4.0 4.12.1 OK -
 libusb libusb - USB library REQUIRED - 1.0 OK -
 cups-image CUPS image - CUPS image development files REQUIRED - 2.2.7 OK -
 python2X Python 2.2 or greater - Python programming language REQUIRED 2.2 2.7.15 OK -
 python-notify Python libnotify - Python bindings for the libnotify Desktop notifications OPTIONAL - - OK -
 libjpeg libjpeg - JPEG library REQUIRED - - OK -
 sane SANE - Scanning library REQUIRED - - OK -

----------------------
| Scan Configuration |
----------------------

 scanext Scan-SANE-Extension REQUIRED - 3.19.3 OK -
 hpaio HPLIP-SANE-Backend REQUIRED - 3.19.3 OK 'hpaio found in /etc/sane.d/dll.conf'

-------------------------
| External Dependencies |
-------------------------

 gs GhostScript - PostScript and PDF language interpreter and previewer REQUIRED 7.05 9.26 OK -
 scanimage scanimage - Shell scanning program OPTIONAL 1.0 1.0.27 OK -
 cups CUPS - Common Unix Printing System REQUIRED 1.1 2.2.7 OK 'CUPS Scheduler is running'
 network network -wget OPTIONAL - 1.19.4 OK -
 policykit PolicyKit - Administrative policy framework OPTIONAL - 0.105 OK -
 xsane xsane - Graphical scanner frontend for SANE OPTIONAL 0.9 0.999 OK -
 dbus DBus - Message bus system REQUIRED - 1.12.2 OK -
 avahi-utils avahi-utils OPTIONAL - 0.7 OK -

---------------------
| Python Extentions |
---------------------

 hpmudext IO-Extension REQUIRED - 3.19.3 OK -
 cupsext CUPS-Extension REQUIRED - 3.19.3 OK -

------------------------------
| DISCOVERED SCANNER DEVICES |
------------------------------

device `hpaio:/net/HP_OfficeJet_Pro_8730?ip=192.168.178.40' is a Hewlett-Packard HP_OfficeJet_Pro_8730 all-in-one
device `hpaio:/net/Officejet_Pro_8500_A910?ip=192.168.178.24' is a Hewlett-Packard Officejet_Pro_8500_A910 all-in-one

--------------------------
| DISCOVERED USB DEVICES |
--------------------------

No devices found.

---------------------------------
| INSTALLED CUPS PRINTER QUEUES |
---------------------------------

HP_OfficeJet_Pro_8730
---------------------
Type: Printer
Device URI: hp:/net/HP_OfficeJet_Pro_8730?ip=192.168.178.40
PPD: /etc/cups/ppd/HP_OfficeJet_Pro_8730.ppd
warning: Failed to read /etc/cups/ppd/HP_OfficeJet_Pro_8730.ppd ppd file
PPD Description:
Printer status: Drucker HP_OfficeJet_Pro_8730 ist im Leerlauf. Aktiviert seit Mi 24 Apr 2019 23:43:52 CEST
Communication status: Good

Officejet_Pro_8500_A910
-----------------------
Type: Printer
Device URI: hp:/net/Officejet_Pro_8500_A910?ip=192.168.178.24
PPD: /etc/cups/ppd/Officejet_Pro_8500_A910.ppd
warning: Failed to read /etc/cups/ppd/Officejet_Pro_8500_A910.ppd ppd file
PPD Description:
Printer status: Drucker Officejet_Pro_8500_A910 ist im Leerlauf. Aktiviert seit Mi 24 Apr 2019 23:51:09 CEST
Communication status: Good

--------------
| PERMISSION |
--------------

No errors or warnings.

Done.

[brian_p (claremont102)]

Probably bug 1797501. Fixed for the 8730 in recent HPLIP versions and can be worked round (bug 1817214).

--
Brian.

[Dirk Reymann (dirkreymann)]

Thanks Brian for the quick response! But it seems, this doesn't really solve the problem.

1. What "recent version" do you refer to, which is supposed to fix the bug? I am already using 3.19.3. Is there a more recent one?

2. It seems, the bug described in #1797501 an #1817214 is still existing in 3.19.3. But for some weird reason, this doesn't disturb the scanning at all.
I am able to find these lines in the journal, which exactly matches the described bug:
Apr 25 15:01:55 user-ThinkPad-T60p hp-scan[4621]: io/hpmud/model.c 532: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 15:01:55 user-ThinkPad-T60p hp-scan[4621]: io/hpmud/model.c 543: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 15:01:55 user-ThinkPad-T60p hp-scan[4621]: io/hpmud/model.c 532: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 15:01:55 user-ThinkPad-T60p hp-scan[4621]: io/hpmud/model.c 543: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
But again: The 8500 has no problem with scanning! (It appears to have AirPrint, but there is no option to turn it off.)

3. (And this is still my main problem...) The behaviour I observe with my 8730 does not match the described bugs.
It has no trouble finding or resolving the 8730.
The 8730 is correctly addressed on the network and the scanning is started.
It is only the image-data transfer back from the AiO-printer to the sane-API which has a bug.

I was able to find these entries in the journal:
Apr 25 15:02:01 user-ThinkPad-T60p hp-scan[4621]: hp-scan[4621]: warning: File destination enabled with no output file specified.
Apr 25 15:02:01 user-ThinkPad-T60p hp-scan[4621]: hp-scan[4621]: warning: Defaulting to '/home/user/hpscan001.png'.
Apr 25 15:02:53 user-ThinkPad-T60p hp-scan[4621]: io/hpmud/jd.c 694: timeout read_channel sec=50 hp:/net/HP_OfficeJet_Pro_8730?ip=192.168.178.40
Apr 25 15:03:05 user-ThinkPad-T60p hp-scan[4621]: scan/sane/http.c 162: read_stream error len=0
   [this line repeats 3750 times...]
Apr 25 15:03:06 user-ThinkPad-T60p hp-scan[4621]: scan/sane/http.c 162: read_stream error len=0
Apr 25 15:03:07 user-ThinkPad-T60p kernel: python[4621]: segfault at bff22000 ip b595cf48 sp bff1ec10 error 4 in libsane-hpaio.so.1.0.0[b594a000+2e000]

--
Dirk

[brian_p (claremont102)]

Ah. I noted "...Mint 19.1 fresh install...", which has HPLIP 3.17.10, but failed to absorb "...HPLIP 3.19.3...". We are on the same page now! 3.19.3 is the newest HPLIP and has a partial fix for bug 1797501. Please see Messages #20, #21 and #22 at bug 1822762.

I also noted "The behaviour I observe with my 8730 does not match the described bugs." and put it on one side because we are in the wonderful world of scanners after all. The 8730 should scan with HPLIP 3.19.3. models.dat has the tag [hp_officejet_pro_8730]. Testing is first done with HP_ removed (it faila and a record should be in the journal) and then it is readded, which should lead to success. Anyway - still thinking.

The 8500 shouldn't be scanning! Its tag is [officejet_pro_8500_a910] and not, as your journal records, [icejet_pro_8500_a910] or [hp_icejet_pro_8500_a910]. Does it still scan if you stop the cups service?

systemctl stop cups.

--
Brian.

[brian_p (claremont102)]

Forgot. Please post the output of

avahi-browse -rt _uscan._tcp

for both scanners. (_scanner._tcp if there is no uscan service).

Thanks.

--
Brian.

[Dirk Reymann (dirkreymann)]

Dear Brian

I'll follow up on your requests later.

I wasn't lazy meanwhile and found out some interesting things... And I got it up and running, at least temporarily.
It seems, it is in fact an unlucky combination of a somehow faulty printer firmware which is not handled properly by hplip.

After a fresh reboot of the printer, scanning works. Sometimes for a few pages only, sometimes much longer. I couln't figure out yet, what causes the system to crash. Actually it doesn't "crash" completely. Something happens to the TCP statemachine!? I am not expert enough to tell, which one is missbehaving, client or printer. I'll post the corresponding wireshark dumps in a minute...

Dirk

PS. Even though it might sound as if I know what I am talking about, I should mention that I have more or less 48 hours experience with Linux. :D LOL I speak C++ fluently, but when it comes to OS details I definitely need a strong helping hand. ;)
Need to read a bit on 'systemctl stop cups' and 'avahi-browse' later...

[Dirk Reymann (dirkreymann)]

Ok. Obviously I am not allowd to attach files here. :-/

So, please have a look there: https://c.1und1.de/@520195727398278735/5SDo4Xf8QgSW1ldlRfUJ-A

* 8730_via_hplip rebooted.pcapng
This is a complete scan after a fresh reboot of the 8730.
Images are handled as expected and ADF, duplex and multi-page scans work fine.
But the protocoll handling still seems to be not 100% correct. The 8730's EWS states the scan jobs to be 'aborted' in about 50% of the time.

* 8730_via_hplip broken.pcapng
This is what happens, after something screwed up. The scan is started. But when the client should continuously poll for the page to be completed, it simply stops after the first attempt.

At the end there is some TCP errors (retransmissions and duplicate ACK). Note the very long delay of 1 minute after this. The next packet after this corresponds to the segmentation fault thrown inside libsane-hpaio.so

In this state, this behaviour is 100% reproducible. Scanning via hplip impossible. Interstingly, printing and also scanning from within Windows work fine as always. So it seems to to be a general network/TCP issue.

[Dirk Reymann (dirkreymann)]

Re: 'systemctl stop cups'...

Simple and straight forward answer: No.
It is very obvious that in my case both AiO-printers had been detected via CUPS only.

user@user-ThinkPad-T60p:~$ systemctl start cups
user@user-ThinkPad-T60p:~$ hp-scan

  Num Scan device URI
  -------- ----------------------------------------------------
  0 hpaio:/net/Officejet_Pro_8500_A910?ip=192.168.178.24
  1 hpaio:/net/HP_OfficeJet_Pro_8730?ip=192.168.178.40

user@user-ThinkPad-T60p:~$ systemctl stop cups
user@user-ThinkPad-T60p:~$ hp-scan
error: No device selected/specified or that supports this functionality.

Apr 25 20:41:06 user-ThinkPad-T60p python[18067]: io/hpmud/model.c 532: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 20:41:06 user-ThinkPad-T60p python[18067]: io/hpmud/model.c 543: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 20:41:06 user-ThinkPad-T60p python[18067]: io/hpmud/model.c 532: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 20:41:06 user-ThinkPad-T60p python[18067]: io/hpmud/model.c 543: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 20:41:11 user-ThinkPad-T60p hp-scan[18067]: hp-scan[18067]: error: No device selected/specified or that supports this functionality.

---------------------------------------------------------------------------------------

Did some more testing, as my 8730 had a few unnessessary protocols disabled.

In fact, it is NOT AirPlay, which makes the difference. It is Bonjour alone.
With Bonjour ON and AirPlay OFF on the 8730 and CUPS still stopped I get this:

Apr 25 20:59:30 user-ThinkPad-T60p hp-scan[18208]: hp-scan[18208]: warning: No destinations specified. Adding 'file' destination by default.
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 532: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 543: no icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 532: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 543: no hp_icejet_pro_8500_a910 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 532: no officejet_pro_8730 attributes found in /usr/share/hplip/data/models/models.dat
Apr 25 20:59:32 user-ThinkPad-T60p hp-scan[18208]: io/hpmud/model.c 543: no officejet_pro_8730 attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
Apr 25 20:59:37 user-ThinkPad-T60p hp-scan[18208]: hp-scan[18208]: warning: File destination enabled with no output file specified.
Apr 25 20:59:37 user-ThinkPad-T60p hp-scan[18208]: hp-scan[18208]: warning: Defaulting to '/home/user/hpscan010.png'.
Apr 25 20:59:38 user-ThinkPad-T60...

[Dirk Reymann (dirkreymann)]

user@user-ThinkPad-T60p:~$ avahi-browse -rt _uscan._tcp
+ wls3 IPv6 HP OfficeJet Pro 8730 [C90C3D] _uscan._tcp local
+ wls3 IPv4 HP OfficeJet Pro 8730 [C90C3D] _uscan._tcp local
= wls3 IPv4 HP OfficeJet Pro 8730 [C90C3D] _uscan._tcp local
   hostname = [HP8730.local]
   address = [192.168.178.40]
   port = [8080]
   txt = ["duplex=T" "is=platen,adf" "cs=binary,color,grayscale" "rs=eSCL" "representation=images/printer.png" "UUID=37481cb7-ce79-5345-c7cb-2c5069ed6e5a" "mopria-certified=1.3" "note=" "adminurl=http://HP8730.local." "ty=HP OfficeJet Pro 8730" "pdl=application/octet-stream,application/pdf,image/jpeg" "vers=2.5" "txtvers=1"]
= wls3 IPv6 HP OfficeJet Pro 8730 [C90C3D] _uscan._tcp local
   hostname = [HP8730.local]
   address = [192.168.178.40]
   port = [8080]
   txt = ["duplex=T" "is=platen,adf" "cs=binary,color,grayscale" "rs=eSCL" "representation=images/printer.png" "UUID=37481cb7-ce79-5345-c7cb-2c5069ed6e5a" "mopria-certified=1.3" "note=" "adminurl=http://HP8730.local." "ty=HP OfficeJet Pro 8730" "pdl=application/octet-stream,application/pdf,image/jpeg" "vers=2.5" "txtvers=1"]

user@user-ThinkPad-T60p:~$ avahi-browse -rt _scanner._tcp
+ wls3 IPv6 HP OfficeJet Pro 8730 [C90C3D] _scanner._tcp local
+ wls3 IPv6 Officejet Pro 8500 A910 [2CA898] _scanner._tcp local
+ wls3 IPv4 HP OfficeJet Pro 8730 [C90C3D] _scanner._tcp local
+ wls3 IPv4 Officejet Pro 8500 A910 [2CA898] _scanner._tcp local
= wls3 IPv4 Officejet Pro 8500 A910 [2CA898] _scanner._tcp local
   hostname = [HP8500.local]
   address = [192.168.178.24]
   port = [8080]
   txt = ["feeder=T" "flatbed=T" "button=T" "note=" "adminurl=http://HP8500.local." "mdl=Officejet Pro 8500 A910" "mfg=HP" "ty=Officejet Pro 8500 A910" "txtvers=1"]
= wls3 IPv6 Officejet Pro 8500 A910 [2CA898] _scanner._tcp local
   hostname = [HP8500.local]
   address = [192.168.178.24]
   port = [8080]
   txt = ["feeder=T" "flatbed=T" "button=T" "note=" "adminurl=http://HP8500.local." "mdl=Officejet Pro 8500 A910" "mfg=HP" "ty=Officejet Pro 8500 A910" "txtvers=1"]
= wls3 IPv4 HP OfficeJet Pro 8730 [C90C3D] _scanner._tcp local
   hostname = [HP8730.local]
   address = [192.168.178.40]
   port = [8080]
   txt = ["feeder=T" "flatbed=T" "button=T" "UUID=37481cb7-ce79-5345-c7cb-2c5069ed6e5a" "mopria-certified=1.3" "note=" "adminurl=http://HP8730.local." "mdl=OfficeJet Pro 8730" "mfg=HP" "ty=HP OfficeJet Pro 8730" "txtvers=1"]
= wls3 IPv6 HP OfficeJet Pro 8730 [C90C3D] _scanner._tcp local
   hostname = [HP8730.local]
   address = [192.168.178.40]
   port = [8080]
   txt = ["feeder=T" "flatbed=T" "button=T" "UUID=37481cb7-ce79-5345-c7cb-2c5069ed6e5a" "mopria-certified=1.3" "note=" "adminurl=http://HP8730.local." "mdl=OfficeJet Pro 8730" "mfg=HP" "ty=HP OfficeJet Pro 8730" "txtvers=1"]

[brian_p (claremont102)]

Thank you for the level of detail, Dirk. We have

> ty=Officejet Pro 8500 A910

and

> ty=HP OfficeJet Pro 8730

The first device should fail scanning and this is substantiated by the four error lines referring to attrubutes in Message #7. A workaround would be to have a section headed [icejet_pro_8500_a910] in models.dat.

The second device should work on HPLIP 3.19.3. This is indicated also by there being only two error lines in Message #7.

If there is anything else going on over and above #1797501, I am afraid my skills are not up to diagnosing it and offering a solution. It is the province of upstream to produce fix.

--
Brian.

[brian_p (claremont102)]

In the first post it was said:

> Scanning on 8500 works fine.

In Message #2 we see

> But for some weird reason, this doesn't disturb the scanning at all.

And in Message #7

> It is very obvious that in my case both AiO-printers had been
> detected via CUPS only.

This bothered me so I ran a test with a Bonjour _scanner._tcp service broadcast for the 8500 and a CUPS queue with an hp:/... URI set up for the printing side. With

  scanimage -L

I got the same four lines about attibutes in the journal as you got, but the mock 8500 was detected. Stop cups and it is not detected.

I have a feeling I have done this in the past but it seems I completely forgot about this fallback mechanism. What I cannot recollect ever seeing is other users making the same observation as you did.

So - many apologies for not picking up on this earlier and perhaps peddling misleading information.

That still leaves a problem 8730, of course.

--
Brian.

[brian_p (claremont102)]

> .....I completely forgot about this fallback mechanism.

This worked to your benefit with the 8500, Dirk. It wouldn't have done if you or anyone else had set up the device with a driverless print queue or a socket://... connection.

--
Brian.

[brian_p (claremont102)]

> That still leaves a problem 8730, of course.

A trustworthy user had this to say in Nov 2018 in Message #87 at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=912768.

 > Concerning the scanning, I have done the following observation:
 >
 > I have the HP OfficeJet Pro 8730.
 >
 > I have removed all print queues using the "hp" CUPS backend
 > (I print with a driverless queue). With an HPLIP-based print
 > queue my scanner is always found.
 >
 > 1. Printer on the network
 >
 > scanimage -L
 >
 > does not find the scanner in my MF device, but
 >
 > scanimage -d hpaio:/net/HP_OfficeJet_Pro_8730?ip=w.x.y.z > x.pnm
 >
 > scans correctly.

Does this command work for you, Dirk? I would guess not.

--
Brian.

[Dirk Reymann (dirkreymann)]

Has been a while, but I'd like to add some newer findings anyway.
I have stopped my Linux experiments on this meanwhile, but some observations with Win7 might give a hint...

Short: It most likely seems to be a weird bug in the OfficeJet Pro 8730 firmware.

Details:
HP8500A + HP8730 printer, Win7 + Win10 clients, AVM FritzBox and TPLink router involved. All running with latest firmware/drivers.

Quite frequently, the Win7 client is unable to initiate neither scanning nor printing on either of the OfficeJets. The HP provided ScanDoctor ist completely helpless on this issue. Doesn't even report a clear problem.
At the same time, ping, connecting the EWS, checking the printer status or ink level, and even updating the IP address for the driver work fine without any problem.

When attempting to either scan or print, die driver on Win7 reports "no connection possible". This affect BOTH OfficeJets.

In this case you can try virtually ANYTHING... Rebooting the PC, re-installing the driver, the beforementioned ScanDoctor, rebooting the router, anything... Nothing helps.

Except for exactly one thing: Rebooting the HP 8730! After this, all functions are immediately and reliably back.
(To point this out very clearly, as weird as it sounds: Scan/print on HP8500 dead. -> Rebooting the HP8730. -> HP8500 is back.)

So, somehow the 8730 is able to completely screw up the whole HP-proprietary communication protocol on the network and rebooting the 8730 immediately solves all problems.

I still haven't found the exacty event that makes the 8730 suddenly misbehave. But the "pattern" (when does it work and when does it fail) I could observes, looks very similar to the hplib problem discussed before.