Why am I unsuccessful in upgrading from 10.04 to 12.04?

Question

A day after the "flummoxed" below, I concede defeat. My laptop will remain on Lucid Lynx until I get a new one. I appreciate people's suggestions and have tried what I could, but do-release-upgrade still does not work for me, as shown in the script below. I wish I had a complete understanding of what the script is telling me. First it goes to the old-releases site to get 10.04 data and then says "Fetched 0B in 0s (0B/s)", which sounds like it fetched nothing. Then it goes to the us.archive.ubuntu site to get 12.04 data and says "Fetched 250 kB in 0s (0 B/s)", which sounds like it found 250 kB. Could the old-releases site be missing necessary data? At any rate, I'm giving up now.

I am still flummoxed, re my question below that starts "In April 2015". I've tried the do-upgrade-release on three different days and always get the same result, so don't think it's a network problem. Let me ask one more question: does anyone know exactly what the message "WARNING: Failed to read mirror file" means? It would be nice if the message named the file it's not reading, and why. Also my script had many lines that began with "Ign" (ignore?), "Hit", and "Err". Err sounds bad, but I'm not sure if Ign and Hit are good, bad, or indifferent. Does anyone understand these messages? Thank you.

In April 2015 I upgraded my desktop from 10.04 to 12.04, but neglected to upgrade my laptop. Now I'm trying to upgrade the laptop from 10.04 to 12.04, but since 10.04 is outdated I must use old-releases-ubuntu in my /etc/apt/sources.list. This is what I did:

• In /etc/apt/sources.list, changed all us.archive.ubuntu and security.ubuntu to old-releases-ubuntu.

  sudo apt-get update && sudo apt-get dist-upgrade
  sudo apt-get update
  sudo apt-get install update-manager-core
  sudo do-release-upgrade
  

  Note: /etc/update-manager/release-upgrades has Prompt=lts

But the do-release-upgrade aborted. Below is a condensation of the script I ran while doing it. I would be grateful for any advice on what I'm doing wrong. Thank you. Also: If this question has already been answered, would you please give me a link to the answer?

NOTE: In the below script, I changed all http:// to URL: and all .com to -com because AskUbuntu won't allow it to be posted if it contains more than 2 links, and removed many lines to avoid being considered spam.

Script started on Sat 06 Feb 2016 04:27:58 PM MST
sudo do-release-upgrade
Checking for a new ubuntu release
Done Upgrade tool signature
Done Upgrade tool
Done downloading
authenticate 'precise.tar.gz' against 'precise.tar.gz.gpg'
extracting 'precise.tar.gz'
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
WARNING: Failed to read mirror file
0% [Connecting to old-releases.ubuntu-com] [Connecting to archive.ubuntu-com]
99% [URL:old-releases.ubuntu-com lucid-security/multiverse Sources 5826B]
Fetched 0B in 0s (0B/s)
Reading package lists... Done
Building dependency tree
Reading state information... 0%
Reading state information... Done
Building data structures... Done
Fetched 0B in 0s (0B/s)
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
0% [Connecting to old-releases.ubuntu-com (91.189.88.17)]
Ign URL:old-releases.ubuntu-com lucid InRelease
Hit URL:old-releases.ubuntu-com lucid/main Sources
26% [URL:old-releases.ubuntu-com lucid-security Release gpgv 58.7 kB]
Ign URL:old-releases.ubuntu-com lucid/main TranslationIndex
Err URL:old-releases.ubuntu-com lucid/main Translation-en
Fetched 0 B in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
Updating repository information
WARNING: Failed to read mirror file
0% [Connecting to us.archive.ubuntu-com (91.189.91.13)]
Ign URL:us.archive.ubuntu-com precise InRelease
Get:1 URL:us.archive.ubuntu-com precise-updates InRelease [196 kB]
1% [1 InRelease 2564 B/196 kB 1%]
Ign URL:us.archive.ubuntu-com precise-security InRelease
Hit URL:us.archive.ubuntu-com precise Release
Fetched 250 kB in 0s (0 B/s)
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done
Calculating the changes
Error authenticating some packages
It was not possible to authenticate some packages. This may be a
transient network problem. You may want to try again later. See below
for a list of unauthenticated packages.
accountsservice
acpi-support
activity-log-manager-common
[...]  (many screens-worth of package-names)
zeitgeist-core
zenity
zenity-common

Restoring original system state
Aborting
Reading package lists... Done    
Building dependency tree          
Reading state information... Done
Building data structures... Done 
=== Command detached from window (Sat Feb  6 16:28:55 2016) ===
=== Command terminated with exit status 1 (Sat Feb  6 16:28:55 2016) ===
[screen is terminating]
exit
Script done on Sat 06 Feb 2016 04:29:25 PM MST