Error with Update Manager and Software Center

A hash mismatch is usually a sign of a broken mirror, so yes, changing mirror was a good approach to take. You can try switching back in a day or two, it may be fixed.

I don't know why you are getting an error on the i18n/Index file, but that's not very important, so you can happily ignore it.

I suggest running rm /var/lib/apt/lists/partial/* /var/lib/apt/lists/*, then trying to update the lists again.

You can do the same operation with these commands:

sudo rm -rf /var/lib/apt/lists/*
sudo apt-get update

this does not work on me.
but if you update at school,you can try this way.

• Click on the system menu at the top right of the screen,

• then click "System Settings".

• Select "Software Sources".

• Under "Download from", click "Other".

• Click "Select Best Server".

• It will then test various servers to find the best one.

Then try running sudo apt-get update again.

I did this, and system found a new server for me, and it works.

Go to /etc/apt/apt.conf and add the following lines and remove the rest of them:

Acquire::http::Proxy "false";

Create proxy settings file for apt:

gksudo gedit /etc/apt/apt.conf.d/80proxy

Add the following line

Acquire::http::Proxy "http://your_proxy:800";

Change your_proxy to the IP address or DNS name of the proxy server. Change the port number to match the proxy port on the server. For me, it is 800. It might differ for your setup.