I also encountered this problem, here's how I fixed it.
The basis of the problem
Put simply, the file layout in Ubuntu 16 changes the location of plymouth themes from
/usr/share/plymouth/themes and so all of the theme install scripts that assumed the previous layout now install to the wrong location. Thus, when update-initramfs runs, the source data is not where it's supposed to be which causes this error.
plymouth module "(/usr/lib/i386-linux-gnu/plymouth//.so)" missing, skipping that theme
and because of that, the theme is not installed. The fallback is the default ubuntu logo theme.
I found it convenient to simply perform things manually, and since you're familiar with Ubuntu, I'll concentrate on describing the approach rather than making it cut-and-paste like.
Partially initialize-correct with apt-get
Run the following command which will not only install a number of new themes into the correct location but also will fix the now incorrect update-alternatives scheme.
apt-get install plymouth-themes
after this runs there will be a new directory structure anchored in
/usr/share/plymouth/themes which will have an identical layout to the previous path.
Move old themes
Consider if each theme is worth migrating, there might be duplicates in which case use the already installed ones.
ls -ltrd /lib/plymouth/themes
ls -ltrd /usr/share/plymouth/themes
migrating to the new location is simple; just move the directory as each theme is contained in a directory named after the theme
mv <theThemeDirectory> /usr/share/plymouth/themes
Fix old themes
The old themes are self-referential in that the .plymouth theme file contains a reference to the directory that the theme is installed. Change these references to the correct ones (e.g.
vi /usr/share/plymouth/themes/orb/orb.plymouth and then replace
Update list with update-alternatives
Extending the orb example, use update-alternatives to make the theme list selectable.
update-alternatives --install /usr/share/plymouth/themes/default.plymouth default.plymouth /usr/share/plymouth/themes/orb/orb.plymouth 100
This has the added benefit of leveraging the script update-plymouth that is included with most themes from gnome-look. I'll include the text
echo "Choose the number of the theme you want to use, then [ENTER]"
sudo update-alternatives --config default.plymouth
sudo update-initramfs -u
read -p "Do you want to test the theme? (Y/N) "
if [ "$REPLY" != "n" -a "$REPLY" != "N" ] ; then
echo "Running 10-second test..."
sudo plymouthd ; sudo plymouth --show-splash ; for ((I=0; I<10; I++)); do sleep 1 ; sudo plymouth --update=test$I ; done ; sudo plymouth --quit
update-plymouth will allow you to select the theme you want, automatically build the new initramfs and let you preview it.
Bonus: use art from deviantart
Armed with this knowledge, we don't blindly have to run an installer, but rather with the understanding that all it takes to install a new theme is
- copy a theme directory to
update-alternatives as described above
That gives us access to larger selection of themes of which I think this sonic theme is the best.