The same here on Trusty:
# apt-get update ... ... Fetched 297 kB in 2s (111 kB/s) W: GPG error: http://de.archive.ubuntu.com trusty-backports Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden> W: Failed to fetch bzip2:/var/lib/apt/lists/partial/de.archive.ubuntu.com_ubuntu_dists_trusty-updates_main_binary-amd64_Packages Hash Sum mismatch
E: Some index files failed to download. They have been ignored, or old ones used instead. # echo $? 100
The same here on Trusty:
# apt-get update de.archive. ubuntu. com trusty-backports Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <email address hidden> var/lib/ apt/lists/ partial/ de.archive. ubuntu. com_ubuntu_ dists_trusty- updates_ main_binary- amd64_Packages Hash Sum mismatch
...
...
Fetched 297 kB in 2s (111 kB/s)
W: GPG error: http://
W: Failed to fetch bzip2:/
E: Some index files failed to download. They have been ignored, or old ones used instead.
# echo $?
100