Fail to install python-pexpect and python-gobject because it 404s

Question

I'm trying to install flux on my Lubuntu 15.10 to do so, I need to install the dependencies python-pexpect and python-gobject.

I have installed python2.7 and python3.4

everytime I try to install the two missing packages (pexpect and gobject), whether I use apt-get install -f or apt-get install git python-pexpect python-gobject

I get the same error: `

Failed to fetch http://fr.archive.ubuntu.com/ubuntu/pool/main/p/pexpect/python-pexpect_3.2-1_all.deb  404  Not Found [IP: 2001:860:f70a::2 80]
`

    E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

I tried both apt-get update and --fix-missing, neither works.

Any help would be greatly appreciated ^_^