I couldn`t upgrade from ubuntu 14.04 to 16.04

[Husain]

Upgrading 14.04 to 16.04 was failed. The response was that you need to go to etc/apt/sources.list and find mirrors. How to solve this problem?

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8 [origin: unknown]
ProcVersionSignature: Ubuntu 4.2.0-42.49~14.04.1-generic 4.2.8-ckt12
Uname: Linux 4.2.0-42-generic i686
ApportVersion: 2.14.1-0ubuntu3.27
Architecture: i386
CrashDB: ubuntu
Date: Thu Nov 30 07:35:08 2017
InstallationDate: Installed on 2017-11-29 (0 days ago)
InstallationMedia:

PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2017-11-30 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2017-11-30 07:32:59.589512
 Log time: 2017-11-30 07:33:20.002483
 Log time: 2017-11-30 07:33:41.923315
 Log time: 2017-11-30 07:35:09.092069
VarLogDistupgradeTermlog: