For a few months now, I've been having issues with the Anki Japanese support add-on. Normally the add-on adds the readings automatically when creating new cards, but lately that was failing with:

An error occurred in an add-on.
Please post on the add-on forum:
https://anki.tenderapp.com/discussions/add-ons

Traceback (most recent call last):
  File "/usr/share/anki/aqt/webview.py", line 18, in run
    return unicode(self._bridge(unicode(str)))
  File "/usr/share/anki/aqt/editor.py", line 462, in bridge
    "editFocusLost", False, self.note, self.currentField):
  File "/usr/share/anki/anki/hooks.py", line 32, in runFilter
    arg = func(arg, *args)
  File "/home/jpichon/.local/share/Anki2/addons/japanese/reading.py", line 209, in onFocusLost
    n[dst] = mecab.reading(srcTxt)
  File "/home/jpichon/.local/share/Anki2/addons/japanese/reading.py", line 76, in reading
    self.ensureOpen()
  File "/home/jpichon/.local/share/Anki2/addons/japanese/reading.py", line 73, in ensureOpen
    raise Exception("Please ensure your Linux system has 32 bit binary support.")
Exception: Please ensure your Linux system has 32 bit binary support.

At first I thought, meh, the rest works fine, and usually I don't need to add the readings for every word anyway, just the one that's new to me in the sentence so that shouldn't take too much time.

It took me a few months to realise I wasn't creating new cards anymore, just plopping them into a list of "cards to create when I have the time someday." Whoops.

The solution, found via a ArchLinux thread is also dead simple:

$ sudo dnf install libstdc++.i686 # Note the i686, that's the important bit!

Better get on with that word list now.