ubiquity crashed with UnicodeDecodeError in decode(): 'ascii' codec can't decode byte 0xc5 in position 8782: ordinal not in range(128)

Status changed to 'Confirmed' because the bug affects multiple users.

Both of March 23rd and March 30th daily build could still reproduce this issue.

Could you share the preseed? It would be useful to reproduce the bug; which I can't seem to get otherwise.

Hi Mathieu, emailed preseed to the reply-to and directly to your gmail on Fri 1st April, hope you got it ok?

I could reproduce this issue with my preseed.
However, if I remove the part of language and keyboard selection of the preseed, and then manually selecting they as English,
this issue could not reproduce and the system would be installed successfully via PXE.

Here is what I removed:

## Locale sets language and country.
#d-i debian-installer/locale string en_US
#
## Keyboard selection.
## Disable automatic (interactive) keymap detection.
#d-i console-setup/ask_detect boolean false
#d-i keyboard-configuration/ask_detect boolean false
##d-i console-setup/modelcode string pc105
#d-i console-setup/layoutcode string us
#d-i keyboard-configuration/layoutcode string us
## To select a variant of the selected layout (if you leave this out, the
## basic form of the layout will be used):
##d-i console-setup/variantcode string dvorak

Sorry for the unclear statement above.
I mean, removing that section of the preseed I used could not reproduce this issue anymore (so I add comment # to remove the section)

I found the issue in localechooser, I will fix it now.

This bug was fixed in the package localechooser - 2.65ubuntu4

---------------
localechooser (2.65ubuntu4) xenial; urgency=medium

  * localechooser: Use grep -a to make sure grep sees our language list data
    as ASCII and not random binary since it contains some glyphs for language
    name translations. Fixes at least one crash in Ubiquity. (LP: #1551285)

 -- Mathieu Trudel-Lapierre <email address hidden> Wed, 13 Apr 2016 10:04:25 -0400

This bug was fixed in the package ubiquity - 2.21.57

---------------
ubiquity (2.21.57) xenial; urgency=medium

  [ Mathieu Trudel-Lapierre ]
  * Automatic update of included source packages: localechooser
    2.65ubuntu4. (LP: #1551285)
  * scripts/simple-plugins: better handle passing the MokPW key to mokutil
    and the result from the command -- we explicitly can ignore errors here.
    (LP: #1567445)
  * plugin-viewer-gtk.py: fix plugin-viewer-gtk to allow showing most plugins
    correctly; useful for debugging.
  * ubiquity/plugins/ubi-prepare.py: rework password validation behavior for
    MokPW without changing user-visible strings: we only need to show feedback
    for a "good" password (of the allowable lengths), and correct the behavior
    for mismatched passwords. Also make it obvious if the chosen password is
    too short. (LP: #1560940)

  [ Shih-Yuan Lee (FourDollars) ]
  * Really make oem-config-prepare quiet when started by a non-priviledged
    user.

 -- Mathieu Trudel-Lapierre <email address hidden> Wed, 13 Apr 2016 14:36:37 -0400