Description of problem:

There are several problems.

First problem:

# hp-plugin -i

HP Linux Imaging and Printing System (ver. 3.17.4)
Plugin Download and Install Utility ver. 2.1

Copyright (c) 2001-15 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.

warning: It is not recommended to run 'hp-plugin' in a root mode.

HP Linux Imaging and Printing System (ver. 3.17.4)
Plugin Download and Install Utility ver. 2.1

Copyright (c) 2001-15 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: Defaults for each question are maked with a '*'. Press <enter> to accept the default.)


-----------------------------------------
| PLUG-IN INSTALLATION FOR HPLIP 3.17.4 |
-----------------------------------------

  Option      Description                                       
  ----------  --------------------------------------------------
  d           Download plug-in from HP (recommended)            
  p           Specify a path to the plug-in (advanced)          
  q           Quit hp-plugin (skip installation)                

Enter option (d=download*, p=specify path, q=quit) ? 

-------------------
| DOWNLOAD PLUGIN |
-------------------

Checking for network connection...
Downloading plug-in from: 
Downloading plug-in: [\                                                                                                                                 ] 0%   error: Plugin download failed with error code = 4

error:  file does not match its checksum. File may have been corrupted or altered

Second problem:

After downloading https://www.openprinting.org/download/printdriver/auxfiles/HP/plugins/hplip-3.17.6-plugin.run and trying to run it manually:

# ./hplip-3.17.6-plugin.run
Verifying archive integrity... All good.
Uncompressing HPLIP 3.17.6 Plugin Self Extracting Archive................................................
Error importing HPLIP modules.  Is HPLIP installed?

The installer (a Python script) fails to import some HPLIP modules.

Third problem:

When copying the *.so plugins into their respective locations, e.g:
/usr/share/hplip/prnt/plugins
/usr/share/hplip/scan/plugins
/usr/share/hplip/fax/plugins

and starting xsane either manually or via xsane-gimp, it refuses to work
as the plugin version doesn't match the HPLIP version:

xsane[3085]: io/hpmud/model.c 532: no 200_colormfp_m276nw attributes found in /usr/share/hplip/data/models/models.dat
xsane[3085]: io/hpmud/model.c 543: no 200_colormfp_m276nw attributes found in /usr/share/hplip/data/models/unreleased/unreleased.dat
xsane[3085]: common/utils.c 188: unable to load library libm.so: /lib64/libm.so: invalid ELF header
xsane[3085]: common/utils.c 130: validate_plugin_version() Plugin version[3.17.4] mismatch with HPLIP version[3.17.6]
xsane[3085]: common/utils.c 157: Plugin version is not matching
xsane[3085]: common/utils.c 220: Invalid Library hanlder pLibHandler = NULL.

Indeed, comparing the *.so files in hplip-3.17.4-plugin.run and
hplip-3.17.6-plugin.run with cmp shows no difference.

Perhaps HP forgot to rebuild the plugins for the new version and packaged
hplip-3.17.6-plugin.run with the old 3.17.4 version.

Downgrading to HPLIP 3.17.4-3.fc26 from Koji makes my scanner work in my
HP LaserJet Pro 200 color MFP M276nw again with the closed source plugin.

Version-Release number of selected component (if applicable):

hplip-3.17.6-1.fc26.x86_64
hplip-common-3.17.6-1.fc26.x86_64
hplip-libs-3.17.6-1.fc26.x86_64
libsane-hpaio-3.17.6-1.fc26.x86_64

hplip-3.17.6-plugin.run

How reproducible:

Always.

Steps to Reproduce:
1. Upgrade Fedora 26 to the latest packages
2. run "hp-plugin -i" or the other tricks
3.

Actual results:

Plugins cannot be installed automatically, only by hand and
the plugin version reported to HPLIP/HPAIO doesn't match and

Expected results:

The plugins should be matching the HPLIP version, therefore the scanner part
of my multifunction printer should work.

Additional info: