The installed version prints correctly, I think scan will work if I enable at least one of those not-installed Synaptic entries- hplip-gui for one.  Faxing from the printer or copying don’t need the computer at all.  Testing the fax function from the computer (i.e. local files) worked with the old pc and the 3.22.4 driver, I’ll have to make arrangements beforehand to test it now- meaning to alert the recipient to be sure their machine is on.

Re Timeshift- this might be a good point to switch from using Veeam- that app takes a full-system image, local files, system files, everything.  Does Timeshift save user files?

Also need a binary plugin, two suggested sequences don’t quite agree:

Also the above mentioned entry in Synaptic.

EDIT- the plugin is listed in Synaptic as well.

Looks like the best move is to see whether all printer functions are enabled using some or all of the not-installed-by-default hplip components in Synaptic.  Back on this later today or  tomorrow, will report back.

Update- all printer drivers listed on Synaptic installed, v. 3.21.8.  All printer functions tested and working as expected except faxing files, target not available until Monday.  Based on hp setup sequence, that faxing will likely work also.

Well… faxing file function will not complete.  I need to get the newer driver package installed, my original project.  Wish me luck…

Just went back and cruised the Mint forum thread mentioned above.  While I marked it as “solved”, the file-faxing issue had not then arisen; also there was considerable difference of opinion and advice over the span of that thread. Never truly found out just which elements of hplip driver pkg are active in that machine.  That is the pc now being retired.  A search on that pc of Synaptic shows the following hplip elements installed:
If there are any other hplip drivers installed, I don’t know how to find them.  Only 4 elements are shown as installed, and the printer has been fully functional, file faxing included, from that computer.

Now, in the replacement pc, by default several of the included hplip- 5 or 6 maybe, were pre-installed and file faxing did not work.  I then went back and installed the rest of the hplip elements in Synaptic except one which does not reference our printer.  Results did not change- attempts to populate the appropriate field with docs to be faxed result in those files’ being diverted to the print queue, and I can prompt the tray icon to show the pop-up at the bottom of the s/shot.  
Bottom line- I still do not know if any of the 3.22.4 drivers are in fact installed on the old machine, have no clue where to find the missing element cited in the second s/shot, or how to re-establish file faxing, a needed function.  The current driver pkg is 3.22.6, the installation of which failed from the Sourceforge site.  For lack of a better idea, I’m about to try it again.

For the record, let me say that by no means am I attempting to be a hero.  I freely admit to being over my head here.  I have little confidence in my computer “skills” and view some of the choices I’m driven to make with apprehension.  It is not lost on me that there are considerable holes in my understanding.  This forum has helped me recover from multiple missteps and I greatly appreciate it.

That said, a little history- I moved into Linux from W7 when it became evident that W10 not only was a problematical release, but that MS was intent on looking over my shoulder.  Dropped anything Google-related for the same reason.  Fast forward a couple of years- a problem with faxing files (a function I occasionally need for safety reasons) arose some time back, and at that time the advice was to install the newest hplip pkg, v. 3.22.4, which was offered on Sourceforge as a CLI install.  My heart rate came mostly back to normal when I found that the procedure, once started, was 98% automatic, and was apparently successful.  The file faxing sequence was functional from then on.  No idea whether that updated driver pkg should then be listed in Synaptic, but it wasn’t- yet something enabled those faxes.  I’m not sure if the newer pkg is installed or not.

Next major crisis arose earlier this year, when Firefox began freezing randomly, several times costing me the loss of half-finished operations.  Turned out to be a widespread although sporadic problem, as yet unresolved AFAIK, and in my case the advice, here and elsewhere, was to replace our vintage 2008 computer.  It has been a challenging effort to get “moved in” from the old machine, but as of now all local files are copied into the new pc.  However- a significant snag is the loss of the file-faxing function.  Having found no guidance as to what to do, I thought back to my previous hplip experience, and attempted to update the driver pkg, first to the current version, and when that failed, to the version I think I installed previously, mentioned above.  All this is out of my comfort range, but I can’t find an alternative.

As of now the old pc is temporarily set up in the basement, with the only available network connection via a wifi antenna, in itself a deviation from the security of a hard-wired hookup.  In addition to this forum, I have inquiries out to the Mint and hplip boards, but I’m still at an impasse.  Please consider my ham-handed efforts as acts of desperation, rather than insouciance.  Still in search of a solution.

mintman wrote:

You need to completely remove all HP Printer drivers and packages you have installed. Go back to the Linux Mint Repo and install the one they have for you. Then after all is working *again* on your computer’s printer look into why the fax is failing. PKCano answered you the last time this happened months ago.

This is what led to the hplip 3.22.4 update mentioned above.  No other corrective solutions found when searching various troubleshooting resources.

DrBonzo wrote:

Slowpoke47, can you get your computer back to the same driver software you had when the fax started to work back around May 11? Perhaps by doing what you did in that Topic?

That was with our old computer, all printer functions were by then and to this day still working.  That machine, which runs Mate 19.2,  remains connected to network on a temporary basis via wifi since hardwired connection to router not an option.

Just ran <hp-check> in Terminal- substantial output including statement that Mint 20.3 is not supported for automatic install along with a list of missing dependencies.  This output lists several communication failures with dates and that is likely when the hplip drivers in Synaptic were temporarily uninstalled.  Perhaps someone more versed in Terminal use can point me in the right direction?

user@user-OptiPlex-5060:~$ hp-check
Saving output in log file: /home/user/hp-check.log

HP Linux Imaging and Printing System (ver. 3.21.8)
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

warning: linuxmint-20.3 version is not supported. Using linuxmint-20.2 versions dependencies to verify and install…

—————
| SYSTEM INFO |
—————

Kernel: 5.4.0-125-generic #141-Ubuntu SMP Wed Aug 10 13:42:03 UTC 2022 GNU/Linux
Host: user-OptiPlex-5060
Proc: 5.4.0-125-generic #141-Ubuntu SMP Wed Aug 10 13:42:03 UTC 2022 GNU/Linux
Distribution: linuxmint 20.3
Bitness: 64 bit

———————–
| HPLIP CONFIGURATION |
———————–

HPLIP-Version: HPLIP 3.21.8
HPLIP-Home: /usr/share/hplip
warning: HPLIP-Installation: Auto installation is not supported for linuxmint distro 20.3 version

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

[hplip]
version=3.21.8

[dirs]
home=/usr/share/hplip
run=/var/run
ppd=/usr/share/ppd/hplip/HP
ppdbase=/usr/share/ppd/hplip
doc=/usr/share/doc/hplip
html=/usr/share/doc/hplip-doc
icon=no
cupsbackend=/usr/lib/cups/backend
cupsfilter=/usr/lib/cups/filter
drv=/usr/share/cups/drv
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=yes
foomatic-drv-install=yes
foomatic-ppd-install=no
foomatic-rip-hplip-install=no
hpcups-install=yes
cups-drv-install=yes
cups-ppd-install=no
internal-tag=3.21.8
restricted-build=no
ui-toolkit=qt5
qt3=no
qt4=no
qt5=yes
policy-kit=yes
lite-build=no
udev_sysfs_rules=no
hpcups-only-build=no
hpijs-only-build=no
apparmor_build=no
class-driver=no

Current contents of ‘/var/lib/hp/hplip.state’ file:
[plugin]
installed = 1
eula = 1
version = 3.21.8

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

[fax]
email_address =
voice_phone =

[installation]
date_time = 09/16/22 07:59:28
version = 3.21.8

[last_used]
device_uri = “hpfax:/net/HP_LaserJet_M1522nf_MFP?ip=192.168.1.4”
printer_name = HP_LaserJet_M1522nf_MFP_fax
working_dir = .

[polling]
device_list =
enable = false
interval = 5

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

[settings]
systray_messages = 0
systray_visible = 0

[upgrade]
last_upgraded_time = 1662634632
notify_upgrade = true
pending_upgrade_time = 0

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

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

error: cups CUPS – Common Unix Printing System REQUIRED 1.1 – INCOMPAT ‘CUPS may not be installed or not running’
gs GhostScript – PostScript and PDF language interpreter and previewer REQUIRED 7.05 9.50 OK –
error: xsane xsane – Graphical scanner frontend for SANE OPTIONAL 0.9 – MISSING ‘xsane needs to be installed’
scanimage scanimage – Shell scanning program OPTIONAL 1.0 1.0.29 OK –
error: dbus DBus – Message bus system REQUIRED – 1.12.16 MISSING ‘DBUS may not be installed or not running’
policykit PolicyKit – Administrative policy framework OPTIONAL – 0.105 OK –
network network -wget OPTIONAL – 1.20.3 OK –
avahi-utils avahi-utils OPTIONAL – 0.7 OK –

————————
| General Dependencies |
————————

error: libjpeg libjpeg – JPEG library REQUIRED – – MISSING ‘libjpeg needs to be installed’
error: cups-devel CUPS devel- Common Unix Printing System development files REQUIRED – – MISSING ‘cups-devel needs to be installed’
error: cups-image CUPS image – CUPS image development files REQUIRED – – MISSING ‘cups-image needs to be installed’
libpthread libpthread – POSIX threads library REQUIRED – b’2.31′ OK –
error: libusb libusb – USB library REQUIRED – 1.0 MISSING ‘libusb needs to be installed’
sane SANE – Scanning library REQUIRED – – OK –
error: sane-devel SANE – Scanning library development files REQUIRED – – MISSING ‘sane-devel needs to be installed’
error: libavahi-dev libavahi-dev REQUIRED – – MISSING ‘libavahi-dev needs to be installed’
error: libnetsnmp-devel libnetsnmp-devel – SNMP networking library development files REQUIRED 5.0.9 – MISSING ‘libnetsnmp-devel needs to be installed’
error: libcrypto libcrypto – OpenSSL cryptographic library REQUIRED – 1.1.1 MISSING ‘libcrypto needs to be installed’
python3X Python 2.2 or greater – Python programming language REQUIRED 2.2 3.8.10 OK –
python3-notify2 Python libnotify – Python bindings for the libnotify Desktop notifications OPTIONAL – – OK –
error: python3-pyqt4-dbus PyQt 4 DBus – DBus Support for PyQt4 OPTIONAL 4.0 – MISSING ‘python3-pyqt4-dbus needs to be installed’
error: python3-pyqt4 PyQt 4- Qt interface for Python (for Qt version 4.x) REQUIRED 4.0 – MISSING ‘python3-pyqt4 needs to be installed’
python3-dbus Python DBus – Python bindings for DBus REQUIRED 0.80.0 1.2.16 OK –
python3-xml Python XML libraries REQUIRED – 2.2.9 OK –
error: python3-devel Python devel – Python development files REQUIRED 2.2 3.8.10 MISSING ‘python3-devel needs to be installed’
python3-pil PIL – Python Imaging Library (required for commandline scanning with hp-scan) OPTIONAL – 7.0.0 OK –
python3-reportlab Reportlab – PDF library for Python OPTIONAL 2.0 3.5.34 OK –

————–
| COMPILEDEP |
————–

error: libtool libtool – Library building support services REQUIRED – – MISSING ‘libtool needs to be installed’
error: gcc gcc – GNU Project C and C++ Compiler REQUIRED – 9.4.0 MISSING ‘gcc needs to be installed’
make make – GNU make utility to maintain groups of programs REQUIRED 3.0 4.2.1 OK –

———————
| Python Extentions |
———————

cupsext CUPS-Extension REQUIRED – 3.21.8 OK –
hpmudext IO-Extension REQUIRED – 3.21.8 OK –

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

‘/etc/sane.d/dll.d/hpaio’ not found.
hpaio HPLIP-SANE-Backend REQUIRED – 3.21.8 OK ‘hpaio found in /etc/sane.d/dll.conf’
scanext Scan-SANE-Extension REQUIRED – 3.21.8 OK –

——————————
| DISCOVERED SCANNER DEVICES |
——————————

device `hpaio:/net/HP_LaserJet_M1522nf_MFP?ip=192.168.1.4′ is a Hewlett-Packard HP_LaserJet_M1522nf_MFP all-in-one

————————–
| DISCOVERED USB DEVICES |
————————–

No devices found.

———————————
| INSTALLED CUPS PRINTER QUEUES |
———————————

Hewlett-Packard-HP-LaserJet-M1522nf-MFP
—————————————
Type: Printer
Device URI: hp:/net/HP_LaserJet_M1522nf_MFP?ip=192.168.1.4
PPD: /etc/cups/ppd/Hewlett-Packard-HP-LaserJet-M1522nf-MFP.ppd
warning: Failed to read /etc/cups/ppd/Hewlett-Packard-HP-LaserJet-M1522nf-MFP.ppd ppd file
PPD Description:
Printer status: printer Hewlett-Packard-HP-LaserJet-M1522nf-MFP disabled since Tue 06 SeBackend /usr/lib/cups/backend/hp does not exist!
Required plug-in status: Installed
Communication status: Good

HP_LaserJet_M1522nf_MFP
———————–
Type: Printer
Device URI: hp:/net/HP_LaserJet_M1522nf_MFP?ip=192.168.1.4
PPD: /etc/cups/ppd/HP_LaserJet_M1522nf_MFP.ppd
warning: Failed to read /etc/cups/ppd/HP_LaserJet_M1522nf_MFP.ppd ppd file
PPD Description:
Printer status: printer HP_LaserJet_M1522nf_MFP disabled since Thu 08 Sep 2022 04:24:04 Backend /usr/lib/cups/backend/hp does not exist!
Required plug-in status: Installed
Communication status: Good

HP_LaserJet_M1522nf_MFP_fax
—————————
Type: Fax
Device URI: hpfax:/net/HP_LaserJet_M1522nf_MFP?ip=192.168.1.4
PPD: /etc/cups/ppd/HP_LaserJet_M1522nf_MFP_fax.ppd
warning: Failed to read /etc/cups/ppd/HP_LaserJet_M1522nf_MFP_fax.ppd ppd file
PPD Description:
Printer status: printer HP_LaserJet_M1522nf_MFP_fax disabled since Mon 12 Sep 2022 03:20File “/usr/lib/cups/filter/hpcupsfax” not available: No such file or directory
Required plug-in status: Installed
Communication status: Good

————–
| PERMISSION |
————–

———–
| SUMMARY |
———–

Missing Required Dependencies
—————————–
error: ‘libcups2’ package is missing/incompatible
error: ‘libdbus-1-dev’ package is missing/incompatible
error: ‘libjpeg8-dev’ package is missing/incompatible
error: ‘libcups2-dev’ package is missing/incompatible
error: ‘cups-bsd’ package is missing/incompatible
error: ‘cups-client’ package is missing/incompatible
error: ‘libcupsimage2-dev’ package is missing/incompatible
error: ‘libusb-1.0.0-dev’ package is missing/incompatible
error: ‘libsane-dev’ package is missing/incompatible
error: ‘libavahi-client-dev’ package is missing/incompatible
error: ‘libavahi-core-dev’ package is missing/incompatible
error: ‘libavahi-common-dev’ package is missing/incompatible
error: ‘python3-dev’ package is missing/incompatible
error: ‘libtool’ package is missing/incompatible
error: ‘libtool-bin’ package is missing/incompatible
error: ‘build-essential’ package is missing/incompatible

Missing Optional Dependencies
—————————–
error: ‘xsane’ package is missing/incompatible

Total Errors: 16
Total Warnings: 0

Done.
user@user-OptiPlex-5060:~$

Back to old pc- Synaptic shows 5 elements of hplip 3.17.10 installed. At the time, installing the rest of the hplip 3.17.10 in Synaptic did not enable faxing.  This is the machine that could not fax until I installed hplip 3.22.4 some months back.  Ran <hp-check>, output shows 3.22.4 is in fact installed, makes sense given the enabling of the fax function.  But more recent advice was to remove all elements of older hplip so as not to conflict w/ newer install.  Just removed them, <hp-check> didn’t work, see Terminal output:

steve@steve-Inspiron-519:~$ hp-check

Command ‘hp-check’ not found, but can be installed with:

sudo apt install hplip

steve@steve-Inspiron-519:~$ sudo apt install hplip
[sudo] password for steve:
Reading package lists… Done
Building dependency tree
Reading state information… Done
The following additional packages will be installed:
hplip-data libhpmud0 libsane-hpaio printer-driver-hpcups
printer-driver-postscript-hp
Suggested packages:
hplip-doc hplip-gui
The following NEW packages will be installed:
hplip hplip-data libhpmud0 libsane-hpaio printer-driver-hpcups
printer-driver-postscript-hp
0 upgraded, 6 newly installed, 0 to remove and 74 not upgraded.
Need to get 8,750 kB of archives.
After this operation, 16.8 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://archive.ubuntu.com/ubuntu bionic/main amd64 hplip-data all 3.17.10+repack0-5 [6,392 kB]
Get:2 http://archive.ubuntu.com/ubuntu bionic/main amd64 libhpmud0 amd64 3.17.10+repack0-5 [108 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic/main amd64 libsane-hpaio amd64 3.17.10+repack0-5 [121 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic/main amd64 printer-driver-hpcups amd64 3.17.10+repack0-5 [251 kB]
Get:5 http://archive.ubuntu.com/ubuntu bionic/main amd64 hplip amd64 3.17.10+repack0-5 [1,035 kB]
Get:6 http://archive.ubuntu.com/ubuntu bionic/main amd64 printer-driver-postscript-hp all 3.17.10+repack0-5 [844 kB]
Fetched 8,750 kB in 3s (2,589 kB/s)
Selecting previously unselected package hplip-data.
(Reading database … 406780 files and directories currently installed.)
Preparing to unpack …/0-hplip-data_3.17.10+repack0-5_all.deb …
Unpacking hplip-data (3.17.10+repack0-5) …
Selecting previously unselected package libhpmud0:amd64.
Preparing to unpack …/1-libhpmud0_3.17.10+repack0-5_amd64.deb …
Unpacking libhpmud0:amd64 (3.17.10+repack0-5) …
Selecting previously unselected package libsane-hpaio:amd64.
Preparing to unpack …/2-libsane-hpaio_3.17.10+repack0-5_amd64.deb …
Unpacking libsane-hpaio:amd64 (3.17.10+repack0-5) …
Selecting previously unselected package printer-driver-hpcups.
Preparing to unpack …/3-printer-driver-hpcups_3.17.10+repack0-5_amd64.deb …
Unpacking printer-driver-hpcups (3.17.10+repack0-5) …
Selecting previously unselected package hplip.
Preparing to unpack …/4-hplip_3.17.10+repack0-5_amd64.deb …
Unpacking hplip (3.17.10+repack0-5) …
Selecting previously unselected package printer-driver-postscript-hp.
Preparing to unpack …/5-printer-driver-postscript-hp_3.17.10+repack0-5_all.deb …
Unpacking printer-driver-postscript-hp (3.17.10+repack0-5) …
Setting up hplip-data (3.17.10+repack0-5) …
Setting up libhpmud0:amd64 (3.17.10+repack0-5) …
Setting up libsane-hpaio:amd64 (3.17.10+repack0-5) …
Setting up printer-driver-hpcups (3.17.10+repack0-5) …
Setting up hplip (3.17.10+repack0-5) …
Creating/updating hplip user account…
Setting up printer-driver-postscript-hp (3.17.10+repack0-5) …
Processing triggers for libc-bin (2.27-3ubuntu1.6) …
Processing triggers for man-db (2.8.3-2ubuntu0.1) …
Processing triggers for dbus (1.12.2-1ubuntu1.3) …
Processing triggers for cups (2.2.7-1ubuntu2.9) …
steve@steve-Inspiron-519:~$

With this done, <hp-check> again reports 3.22.4 installed, all functional.  Seems to be no conflict between the two versions.  Note the contrast between the Terminal output from command <hp-check> from new pc (posted above) and this output.

Also learned- apps installed outside of Synaptic are not added to Synaptic repo.

DrBonzo wrote:

What did you then do that resulted in saying 3.22.4 was installed?

Look at the first few lines of that Terminal output- instructions were to reinstall 3.17.10.  Then <hp-check> generated the rest of the output.

DrBonzo wrote:

it says the version 3.22.2 added support for Mint 20.3. If that’s true I would expect that 3.22.4 would also support Mint 20.3. And yet 3.22.4 apparently doesn’t work?. It also says that 3.21.8 added support for Mint 20.2, which implies that 3.21.8 doesn’t support Mint 20.3. But if 2.21.8 doesn’t support Mint 20.3, why is it installed on my Mint 20.3 computer? I’ve never installed it.

All good questions. No answers here.  See Terminal output from new pc (earlier of the two posts).  I’m with you- why would Terminal say not supported, while it’s listed in Synaptic?

No time just now to follow up, but a member on the Mint forum says he installed 3.22.2  when he couldn’t get anywhere with .4 or .6.  His OS is 21.

New instance of Mate 20.3 appears to be correct, Veeam and Musescore apps installed, also seem correct.  Just found this tutorial:

https://developers.hp.com/hp-linux-imaging-and-printing/install/install/index

Looks like the official path to hplip install.  Planning to use v. 3.22.4 which I know from past experience enables all printer functions and seems that these steps prevent any possible interference of Mate-included older hplip version with new install.  Also I learned on this page the difference between a run file and tarball, at least in this instance- run is for automatic install and tar.gz is for manual.  A little further study before starting.  If you hear a cry of anguish from coastal RI, US- the install failed.

Well… no joy.  The Mate install appears correct, two other apps not in Synaptic now installed.  Used the same tutorial as in the old pc for hplip:

https://developers.hp.com/hp-linux-imaging-and-printing/install/install/index

Opted for the automatic install, version hplip-3.22.4, which uses the .run file- that tutorial renders the user mostly an observer, a little input here and there. The install went great… until the plugin install at the end.   This returned an error message, “checksums do not match” so, no plugin and limited printer function.  The installer found both downloads no problem.  Just for the heckuvit, ran the same sequence with 3.22.2 and .6, same result each time.  The Mate-supplied hplip pkg, (3.21.8), which didn’t support faxing (thus leading to this adventure) was uninstalled before beginning.

Now- chapter 2- back to the old machine today (runs Mate 19.2), the hplip appearance was a little “odd” so I reinstalled the pkg and plugin (3.22.4, as before) from the same sources as used in the effort described above.  BUT- in this pc, the install AND the plugin went right in, no hiccups.  After doing that, I confirmed that all printer functions are 100%, faxing included.  This is as it has been since last April when that pkg was installed.

The only thing at variance is the newer Mate install in the new pc.  Could it be that 20.3 does not fully support the hplip suite?  And, if yes, what are the chances for an update to come along and address this deficiency?  Can a mere mortal lobby the Mint developers?

All these suggestions appreciated.  As you can see by my earlier post, I’m looking for the “cleanest” possible method.  We fax files only occasionally, but always for an important reason.  No permanent place available in the office for the old computer, currently set up on a workbench in the middle of my woodworking shop and tucked in with an old sheet.  A dual boot is a possibility.  The fax site mentioned above lists several options that don’t involve subscribing to an online fax service, which would be counterproductive to the need for privacy.  There are external fax modems available for not much money, another possibility if I cannot win with the current setup.  That last choice is, of course, preferred.

Well… sometimes life throws you a bone.  After all efforts to get file faxing enabled on this new pc, I put this on back burner about 3 weeks ago, leaving hplip 3.22.2 installed in lieu of the default 3.21.8.  The file-faxing procedure failed due to “missing plugin” on 3.22.2, .4, and .6.  Plugin not available.  At that time I had sent an email to Clement Lefebvre, but had no response.

Fast forward to yesterday- first attempt to scan with this machine returned error message “plugin needed” and presented an option to retrieve and install said plugin.  With plugin installed, scan completed.  On a whim I then tried the faxing function, and waddya know- successfully faxed test file from home page!

Sometimes procrastinating pays off…

OP here- this saga has a happy ending, but a final comment is needed.  My success in my previous post was temporary.  Finally dawned on me to run <hp-check> and the output included a warning- Mint 20.3 does not support automatic install.  I had been trying to do just that, using the HP tutorial and the .run file.  Several dependencies were missing.

I then downloaded the hplip3.22.4 tarball and installed it using this tutorial- How to install hplip on Ubuntu – Edoardo Vignati  Completed a couple of days ago, all functions including file faxing performing like clockwork.  Well pleased to have this resolved.  Unlike email with attachments, AFAIK a fax is unhackable.