Jtdcftul

I gave the following command:

% sudo do-release-upgrade -d



Here is my screen output: 



Checking for a new Ubuntu release

Get:1 Upgrade tool signature [819 B]                                           

Get:2 Upgrade tool [1,263 kB]                                                  

Fetched 1,264 kB in 0s (0 B/s)                                                 

authenticate 'bionic.tar.gz' against 'bionic.tar.gz.gpg' 

extracting 'bionic.tar.gz'



Reading cache



Checking package manager

Reading package lists... Done

Building dependency tree        

Reading state information... Done

Hit http://archive.canonical.com/ubuntu xenial InRelease                       

Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [107 kB]     

Hit http://us.archive.ubuntu.com/ubuntu xenial InRelease                       

Get:2 http://security.ubuntu.com/ubuntu xenial-security/main Sources [139 kB]  

Get:3 http://security.ubuntu.com/ubuntu xenial-security/universe Sources [89.7 kB]

Get:4 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages [589 kB]

Get:5 http://security.ubuntu.com/ubuntu xenial-security/main i386 Packages [502 kB]

Get:6 http://security.ubuntu.com/ubuntu xenial-security/main Translation-en [245 kB]

Get:7 http://security.ubuntu.com/ubuntu xenial-security/universe amd64 Packages [408 kB]

Get:8 http://security.ubuntu.com/ubuntu xenial-security/universe i386 Packages [354 kB]

Get:9 http://security.ubuntu.com/ubuntu xenial-security/universe Translation-en [159 kB]

Fetched 2,593 kB in 6s (352 kB/s)                                              

Reading package lists... Done    

Building dependency tree          

Reading state information... Done



Restoring original system state



Aborting

Reading package lists... Done    

Building dependency tree          

Reading state information... Done

I tried searching for all similar issues on this and other forums. But none of them helped. Please let me know if any other output or diagnostic message I should print. Any help will be greatly appreciated.

I have been periodically trying to upgrade using the traditional way and every time I failed the same way I described above.

Until today (3/17/2019).

There was an automatic update (not upgrade) that happened that must have brought in the required fix.

I tried again. And, after 4 hours of file downloading and installing, lo and behold, I am now using 18.04 LTS.

I still want to know what was wrong that was fixed in the update. But if you saw the same error that I had, go ahead and upgrade now.