Package: firebird3.0-server Version: 3.0.1.32609.ds4-14 Severity: normal Thanks to Fritz Elfert who diagnosed this and proposed the fix.
When firebird3.0-server is installed via apt, apt first tries to configure the package. The .config script reads the password via debconf and then resets the question. Later, in the .postinst script, the password is not available. The fix is to move the resetting of the password question from the .config script to the .postinst script. -- System Information: Debian Release: 9.0 APT prefers unstable APT policy: (500, 'unstable'), (1, 'experimental') Architecture: amd64 (x86_64) Kernel: Linux 4.9.0-2-amd64 (SMP w/4 CPU cores) Locale: LANG=bg_BG.UTF-8, LC_CTYPE=bg_BG.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) Versions of packages firebird3.0-server depends on: ii adduser 3.115 ii debconf 1.5.60 ii firebird3.0-common 3.0.1.32609.ds4-14 ii firebird3.0-common-doc 3.0.1.32609.ds4-14 ii firebird3.0-server-core 3.0.1.32609.ds4-14 ii firebird3.0-utils 3.0.1.32609.ds4-14 ii init-system-helpers 1.47 ii libc6 2.24-9 ii libfbclient2 3.0.1.32609.ds4-14 ii libgcc1 1:6.3.0-10 ii libncurses5 6.0+20161126-1 ii libstdc++6 6.3.0-10 ii libtinfo5 6.0+20161126-1 ii libtommath1 1.0-4 ii lsb-base 9.20161125 Versions of packages firebird3.0-server recommends: ii libib-util 3.0.1.32609.ds4-14 Versions of packages firebird3.0-server suggests: ii firebird3.0-doc 3.0.1.32609.ds4-14