Comment 9 for bug 1534374

Well, I think I not alone in this. I am trying to update from 14.10 to 15.04 but it seems impossible. First I had the issue "Cannot calculate upgrade" and after entering a bunch of lines on the terminal relating to Xorg and other third party packages, I still unable to update.

On the step of "Calculating changes" Now, the error I get is this:

"Calculando los cambios

Calculando los cambios

Error al autenticar algunos paquetes

No ha sido posible autenticar algunos paquetes. Esto puede ser debido
a un problema transitorio en la red. Pruebe de nuevo más tarde. Vea
abajo una lista de los paquetes no autenticados.

gettext
libatomic1
libfftw3-double3
libfftw3-single3
libgfortran3
libgomp1
libitm1
libquadmath0
libstdc++6
libstdc++6:i386
libtsan0

the packages above mentioned "could not be authenticated"

I really would like to go ahead with the automatic upgrade. i don't want to go through installing it from a usb or dvd.

I have upgraded from older versions till the current I have.