I did that before getting this e-mail.  Actually I deleted EVERYTHING
relating to printing and scanning and installed hplip and other packages one
at a time until things worked again.

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On Thu, 27 Aug 2020, Till Kamppeter wrote:

> Date: Thu, 27 Aug 2020 14:20:41 -0000
> From: Till Kamppeter <email address hidden>
> To: <email address hidden>
> Subject: [Bug 1871011] Re: USB scanning broken on focal --> hpmud and ippusbxd
>      conflict
> 
> Please uninstall ippusbxd. Then your device should work with HPLIP
> normally. ippusbxd wa supposed to allow driverless printing and scanning
> without HPLIP. Unfortunately there were problems in its design.
>
> In Groovy we will replace ippusbxd by ipp-usb which finally allows
> driverless printing and scanning without HPLIP to work reliably.
>
> See bug 1891157.
>
> -- 
> You received this bug notification because you are subscribed to a
> duplicate bug report (1873748).
> https://bugs.launchpad.net/bugs/1871011
>
> Title:
>  USB scanning broken on focal --> hpmud and ippusbxd conflict
>
> Status in HPLIP:
>  Invalid
> Status in hplip package in Ubuntu:
>  Expired
>
> Bug description:
>  On Ubuntu 20.04 focal (with -proposed enabled). HPLIP=3.20.3.
>
>  Previously there was a libmtp (udev) bug erroneously detecting HP
>  printers as mtp devices. This was fixed. Now, I can try to scan-- from
>  both simple-scan and hp-scan, hplip errors out:
>
>
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 427: Found interface conf=0, iface=1, altset=0, index=1
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 389: Active kernel driver on interface=1 ret=0
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 515: invalid claim_interface 7/1/2: Device or resource busy
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 427: Found interface conf=0, iface=0, altset=1, index=3
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 389: Active kernel driver on interface=0 ret=0
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 515: invalid claim_interface 7/1/4: Device or resource busy
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 427: Found interface conf=0, iface=3, altset=0, index=9
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 389: Active kernel driver on interface=3 ret=0
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 515: invalid claim_interface ff/4/1: Device or resource busy
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 427: Found interface conf=0, iface=0, altset=0, index=11
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 389: Active kernel driver on interface=0 ret=0
>  Apr 05 21:27:37 dani-mbp15 simple-scan[3464]: io/hpmud/musb.c 515: invalid claim_interface ff/cc/0: Device or resource busy
>
>  Printer/scanner is an Officejet 4635. Scanning previously worked just
>  fine a few months ago. Regression?
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/hplip/+bug/1871011/+subscriptions
>