Summary of my private reply to Andreas for the record: 1) I only use FTP backends 2) Yes all apt-get clients ran flawlessly before the upgrade with apt-proxy and Twisted in Sarge. Actually I upgraded to Sid due to other reasons and I'm not sure I will downgrade as there are core packages which I need to be newer than in Sarge or Testing without pinning etc. 3) I can imagine apt-proxy having other bugs which only surfaced now in Sid and with the new Twisted 4) I may turn on debug logs and try again
