Well, that's weird ! I would say if that the problem why don't you backup your data and then try performing a factory reset !! Once done then again try updating ... I know this solution do sounds a little more extreme but I would still say it will work out for you !
Wiping the cache works for me. I followed all the steps as per instruction provided. Now able to update my Nexus to 5.0.2. Thank you once again.Cheers !!!
Well, it hasn't worked for me.
I have a 32G N7 2012 only wifi model.
Suddenly since 1 week, it started showing only 6 G as the total space.
Tried the wiping the cache - but did not help.
Will be trying to factory reset.
Keeping fingers crossed