The other night I had an "accident" and powered off my computer at the wall! Worse than the normal risks I had a VM running Fedora in the middle of an update!
When I powered on again and got back to where I "left off" I started to get errors from yum.
[root at ???????? root]# yum update
Gathering header information file(s) from server(s)
Server: Fedora Core 1 - i386 - Base
Traceback (most recent call last):
File > /usr/bin/yum", line 60, in ?
yummain.main(sys.argv[1:])
File "yummain.py", line 188, in main
File "clientStuff.py", line 766, in get_package_info_from_servers
File "clientStuff.py", line 103, in HeaderInfoNevralLoad
ValueError: unpack list of wrong size
I fiddled around with retries for ages but to no avail. So it was Google time with "unpack list of wrong size". Not much digging took me to a website I'd been to before and seems very helpful. You'll find it at https://lists.dulug.duke.edu/pipermail/yum/2003-December/003225.html
If you follow the thread it becomes obvious that the fault is indicating that the cached headers, etc. have become corrupted and deleting them is the only answer. But don't try deleting the whole directory at '/var/cache/yum' and then trying 'yum update' as it'll whinge that it 'can't find /var/cache/yum/base directory'. just delete the contents of '/var/cache/yum/ base' and '/var/cache/yum/updates-released' and you'll have the pleasure of watching the whole set of headers being downloaded again, followed by a successful update completing.