[Bug 1062018] [NEW] I cannot update or install softwares

[Yomal Amarathunge]

Public bug reported:

When i am going to install the updates using update Manager, a error messege comes and it says:
Requires installation of untrusted packages

The action would require the installation of packages from not
authenticated sources.

I dont know how to correct this error.In previous weeks (before i updtae the update maneger programme) i was able to install any software and update.But now,the above error comes always
help me please
Description:	Ubuntu 12.04.1 LTS
Release:	12.04

** Affects: update-manager (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1062018

Title:
  I cannot update  or install softwares

Status in “update-manager” package in Ubuntu:
  New

Bug description:
  When i am going to install the updates using update Manager, a error messege comes and it says:
  Requires installation of untrusted packages

  The action would require the installation of packages from not
  authenticated sources.

  I dont know how to correct this error.In previous weeks (before i updtae the update maneger programme) i was able to install any software and update.But now,the above error comes always
  help me please
  Description:	Ubuntu 12.04.1 LTS
  Release:	12.04

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