The problem seems to manifest in UpdateManager/Core/DistUpgradeFetcherCore.py , in method DistUpgradeFetcherCore.authenticate:
authenticate '/tmp/tmpy-qZkJ/feisty.tar.gz' against '/tmp/tmpy-qZkJ/feisty.tar.gz.gpg'
The latter does not exist on the local machine, neither in the apt-cacher cache.
The problem seems to manifest in UpdateManager/ Core/DistUpgrad eFetcherCore. py , in method DistUpgradeFetc herCore. authenticate:
authenticate '/tmp/tmpy- qZkJ/feisty. tar.gz' against '/tmp/tmpy- qZkJ/feisty. tar.gz. gpg'
The latter does not exist on the local machine, neither in the apt-cacher cache.