Hi Tobias, thank you for getting in touch! I just tried installing the manuskript snap, and verified that indeed it does not start. After a few seconds it prints this line:

    Qt: Session management error: Could not open network socket

I'm not sure where this error comes from; I suspected that it could be coming from the QSessionManager class, but a quick grep in manuskript source code did not find anything (though maybe it's being used by some of manuskript's dependencies?).

A useful tool to debug such cases is `snappy-debug`: you just start it with the -f flag, and then start the application you want to debug:

    snappy-debug -f

This will start monitoring the system log for error messages, and print out some information that might be useful to fix the issue. In our case, it prints:

===================
= AppArmor =
Time: Dec 14 09:50:27
Log: apparmor="DENIED" operation="capable" profile="/snap/core/11993/usr/lib/snapd/snap-confine" pid=16204 comm="snap-confine" capability=4  capname="fsetid"
Capability: fsetid
Suggestions:
* adjust program to not require 'CAP_FSETID' (see 'man 7 capabilities')
* add one of 'account-control' to 'plugs'
* do nothing if program otherwise works properly

= AppArmor =
Time: Dec 14 09:50:56
Log: apparmor="DENIED" operation="open" profile="snap.manuskript.manuskript" name="/proc/16204/mounts" pid=16204 comm="python3" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/16204/mounts (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mounts'
* add one of 'mount-observe, network-control' to 'plugs'

= Seccomp =
Time: Dec 14 09:50:58
Log: auid=1000 uid=1000 gid=1000 ses=3 pid=16204 comm="python3" exe="/snap/manuskript/467/usr/bin/python3.6" sig=0 arch=c000003e 41(socket) compat=0 ip=0x7efe6992dd57 code=0x50000
Syscall: socket
Suggestions:
* add account-control (if using NETLINK_AUDIT)
* add audio-playback (if using NETLINK_KOBJECT_UEVENT)
* add bluetooth-control (if using AF_{ALG,BLUETOOTH})
* add firewall-control (if using NETLINK_{FIREWALL,IP6_FW,NETFILTER,NF_LOG,ROUTE})
* add hardware-observe (if using NETLINK_{GENERIC,KOBJECT_UEVENT})
* add netlink-audit (if using NETLINK_AUDIT)
* add netlink-connector (if using NETLINK_CONNECTOR)
* add network (if using AF_INET{,6}, AF_CONN, NETLINK_ROUTE)
* add network-bind (if using AF_INET{,6}, NETLINK_ROUTE)
* add network-control (if using AF_{APPLETALK,BRIDGE,INET,INET6,IPX,PACKET,PPPOX,SNA}, NETLINK_{DNRTMSG,FIB_LOOKUP,GENERIC,INET_DIAG,ISCSI,KOBJECT_UEVENT,RDMA,ROUTE,XFRM})
* add network-observe (if using SOCK_RAW, AF_INET{,6}), NETLINK_{GENERIC,INET_DIAG,KOBJECT_UEVENT,ROUTE})
* add raw-usb (if using NETLINK_KOBJECT_UEVENT)
* add time-control (if using NETLINK_AUDIT)
* add unity7 (if using NETLINK_KOBJECT_UEVENT)
* add upower-observe (if using NETLINK_KOBJECT_UEVENT)
* add x11 (if using NETLINK_KOBJECT_UEVENT)

= AppArmor =
Time: Dec 14 09:50:58
Log: apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/NetworkManager" interface="org.freedesktop.DBus.Properties" member="GetAll" mask="send" name="org.freedesktop.NetworkManager" pid=16204 label="snap.manuskript.manuskript" peer_pid=3317 peer_label="unconfined"
DBus access
Suggestion:
* try adding one of 'network-manager, network-manager-observe' to 'plugs'
===================

There are a few things we can do at this point. The first one, in my opinion, is to figure out where in manuskript code these operations are triggered, and understand what they are used for, and whether they are really needed (maybe there are other ways to accomplish the same task).

Once we have decided that all these operations are necessary, we need to find out which of the denials above is actually preventing the application from working: it's very well possible that not all of the denials are fatal, and maybe we just need to fix one of them. The instructions given by Ian in the forum thread you linked to (https://forum.snapcraft.io/t/request-for-auto-connection-of-jami-network-manager/22833/17) can be adapted here too.

Please let me know if you manage to find out what exactly is blocking manuskript, and then we can discuss on how to proceed.

Also related:
- https://github.com/olivierkes/manuskript/issues/678
- https://github.com/olivierkes/manuskript/issues/900