[Bug 1608799] [NEW] not able to upgrade from 14.04 to 16.04.1

[mahesh]

Public bug reported:

While updating ubuntu 14.04 to 16.04.1............

$sudo do-release-upgrade


An unresolvable problem occurred while calculating the upgrade. 

This can be caused by: 
* Upgrading to a pre-release version of Ubuntu 
* Running the current pre-release version of Ubuntu 
* Unofficial software packages not provided by Ubuntu 

If none of this applies, then please report this bug using the 
command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. 


Restoring original system state

Aborting
Reading package lists... Done    
Building dependency tree          
Reading state information... Done
Building data structures... Done

** Affects: ubuntu-release-upgrader (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1608799

Title:
  not able to upgrade from 14.04 to 16.04.1

Status in ubuntu-release-upgrader package in Ubuntu:
  New

Bug description:
  While updating ubuntu 14.04 to 16.04.1............

  $sudo do-release-upgrade

  
  An unresolvable problem occurred while calculating the upgrade. 

  This can be caused by: 
  * Upgrading to a pre-release version of Ubuntu 
  * Running the current pre-release version of Ubuntu 
  * Unofficial software packages not provided by Ubuntu 

  If none of this applies, then please report this bug using the 
  command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal. 

  
  Restoring original system state

  Aborting
  Reading package lists... Done    
  Building dependency tree          
  Reading state information... Done
  Building data structures... Done

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