Hi! Commit https://salsa.debian.org/apt-team/apt/-/commit/ebca2f25 affects the behviour of apt under proot. However I don't know enough about proot and about code changed in the commit. Therefore I don't know if commit ebca2f25 is a proper fix for this ticket, and I can't close this ticket.
Ticket fixed by commit ebca2f25: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=806475 Successful reproduction in commit d5e7aa2a preceding the commit in question (apt built from sources): acerion@debian:~/ticket/pre_fix$ grep PRETTY_NAME /etc/os-release PRETTY_NAME="Debian GNU/Linux 9 (stretch)" acerion@debian:~/ticket/pre_fix$ apt --version apt 1.1.1 (amd64) acerion@debian:~/ticket/pre_fix$ proot -0 apt-get download 0ad E: Method gave invalid 400 URI Failure message: Could not switch group, user _apt is still in group 24 E: Method http has died unexpectedly! E: Sub-process http returned an error code (112) acerion@debian:~/ticket/pre_fix$ Unsuccessful reproduction in commit ebca2f25 (apt built from sources): acerion@debian:~/ticket/post_fix$ grep PRETTY_NAME /etc/os-release PRETTY_NAME="Debian GNU/Linux 9 (stretch)" acerion@debian:~/ticket/post_fix$ apt --version apt 1.1.1 (amd64) acerion@debian:~/ticket/post_fix$ proot -0 apt-get download 0ad Get:1 http://archive.debian.org/debian stretch/main amd64 0ad amd64 0.0.21-2 [5,230 kB] Fetched 5,230 kB in 0s (8,460 kB/s) acerion@debian:~/ticket/post_fix$ Kamil
