Comment 3 for bug 927285

Still affects 12.04 release. This is manual FIX.

I stuck on that problem when building my mini-itx atom backend platform with RAID and LVM. Inspired by workaround of bug 976509 given in comment #8 I started filenames investigation. File name of missing package "fs-secondary-modules-..." was TRUNCATED TO 65 CHARS. In my case file on flashdrive looked like this:
"pool/main/l/linux/fs-secondary-modules-3.2.0-23-generic-pae-di_3.2.0-23.36_i386.ude"
but extension should be "udeb" instead of "ude"!
Note that you can find more 65-chars names truncated that wrongly ends with "ude", so search & fix them all.

12.04 alternate may fail later on installing package "xserver-xorg-video-ati" (bug #789898 resurrection?).
 In my case it was due to another wrongly mangled filename. I found package name misspelled, it was
"xserver-xorg-video-radeon_6.14.99~git20111219.aacbd629-0ubunt_i386.deb"
but should be
"xserver-xorg-video-radeon_6.14.99~git20111219.aacbd629-0ubuntu2_i386.deb"
note truncation before suffix "_i386.deb"

After that one I could successfully finalize installation.