First, I can confirm the problem also appears on amd64. Second: yes, it also appears with 0.11.4-1~bpo10+1.
$ apt show prosody Package: prosody Version: 0.11.4-1~bpo10+1 Status: install ok installed Priority: optional Section: net Maintainer: Debian XMPP Maintainers <pkg-xmpp-de...@lists.alioth.debian.org> Installed-Size: 1.638 kB Provides: xmpp-server Depends: adduser, lsb-base, lua-expat (>= 1.2.0), lua-filesystem (>= 1.4.2-3~), lua5.2, lua5.2-bitop, lua5.2-expat, lua5.2-filesystem, lua5.2-sec, lua5.2-socket, ssl-cert, libc6 (>= 2.17), libidn11 (>= 1.13), libssl1.1 (>= 1.1.0) Recommends: lua5.2-event Suggests: lua-dbi-mysql, lua-dbi-postgresql, lua-dbi-sqlite3, lua-zlib Conflicts: prosody-modules (<< 0.0~hg20170719.cd828b1cb5b9+dfsg-1) Homepage: http://www.prosody.im/ Download-Size: unbekannt APT-Manual-Installed: yes APT-Sources: /var/lib/dpkg/status Description: Lightweight Jabber/XMPP server Prosody is a modern XMPP communication server. It aims to be easy to set up and configure, and efficient with system resources. Additionally, for developers it aims to be easy to extend and give a flexible system on which to rapidly develop added functionality, or prototype new protocols. N: Es gibt 1 zusätzlichen Eintrag. Bitte verwenden Sie die Option »-a«, um ihn anzuzeigen. $ sudo ejabberd2prosody /tmp/dump.txt lua: /usr/lib/prosody/util/stanza.lua:27: module 'util.encodings' not found: no field package.preload['util.encodings'] no file '/usr/local/share/lua/5.2/util/encodings.lua' no file '/usr/local/share/lua/5.2/util/encodings/init.lua' no file '/usr/local/lib/lua/5.2/util/encodings.lua' no file '/usr/local/lib/lua/5.2/util/encodings/init.lua' no file '/usr/share/lua/5.2/util/encodings.lua' no file '/usr/share/lua/5.2/util/encodings/init.lua' no file './util/encodings.lua' no file '/usr/lib/prosody/util/util/encodings.lua' no file '/usr/lib/prosody/util/encodings.lua' no file '/usr/bin/../util/encodings.lua' no file '/usr/bin/util/encodings.lua' no file '/usr/local/lib/lua/5.2/util/encodings.so' no file '/usr/lib/x86_64-linux-gnu/lua/5.2/util/encodings.so' no file '/usr/lib/lua/5.2/util/encodings.so' no file '/usr/local/lib/lua/5.2/loadall.so' no file './util/encodings.so' no file '/usr/bin/../util/encodings.so' no file '/usr/local/lib/lua/5.2/util.so' no file '/usr/lib/x86_64-linux-gnu/lua/5.2/util.so' no file '/usr/lib/lua/5.2/util.so' no file '/usr/local/lib/lua/5.2/loadall.so' no file './util.so' no file '/usr/bin/../util.so' stack traceback: [C]: in function 'require' /usr/lib/prosody/util/stanza.lua:27: in main chunk [C]: in function 'require' /usr/bin/ejabberd2prosody:28: in main chunk [C]: in ? -- Blog: https://mg.guelker.eu