It's a good idea, and in some cases a requirement, to rebuild your wiki
when upgrading to a new version of ikiwiki. If you have a lot of different
wikis on a system, this can be a pain to do by hand, and it's a good idea
to automate it anyway.
This Debian package of ikiwiki supports rebuilding wikis on upgrade. It
will run ikiwiki-mass-rebuild if necessary when upgraded. The file
/etc/ikiwiki/wikilist lists the setup files of wikis to rebuild, as well
as the user who owns the wiki. Edit this file and add any wikis you
set up.