unable to update the vm using apt-get update, throwing 403 permission denied error

[kailashms]

Hi All,

I have 4 Ubuntu 1604 boxes and when i want to install any package it tells , 403 forbidden error.
we have tried to run below commands

#apt-get clean
#cd /var/lib/apt
mv lists lists_old
mkdir -p lists/partial
apt-get clean
apt-get update

But afte this also we could see the same issue.
We have removed the file and copied the content from a working vm, but still the same.

when we try to install any package we get the following error

cat /etc/apt/sources.list|grep "xenial-updates"
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package walinuxagent is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'walinuxagent' has no installation candidate
root@SMULWEBPM2U001:~# apt-get search walinuxagent
E: Invalid operation search
root@SMULWEBPM2U001:~# apt-get search walinuxagent
E: Invalid operation search
root@SMULWEBPM2U001:~# apt search walinuxagent
Sorting... Done
Full Text Search... Done
root@SMULWEBPM2U001:~# apt search WALinuxAgent
Sorting... Done
Full Text Search... Done
root@SMULWEBPM2U001:~# apt-get install elinks
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package

Any assistance on this highly appreciated

Thanks Kailash B