snapd is dead and panic when trying to start

[Anthony Wong]

I have a snap that uses the camera interface. This is what I did:

$ sudo snap connect dash:camera ubuntu-core:camera
$ sudo snap disconnect dash:camera

error: cannot perform the following tasks:
- Disconnect : from dash:camera (cannot disconnect plug from slot "camera" from snap "dash", no such slot)
$ sudo snap disconnect ubuntu-core:camera
[|] Disconnect : from ubuntu-core:camera

error: cannot communicate with server: Get http://localhost/v2/changes/138: dial unix /run/snapd.socket: connect: connection refused

After that, when I 'systemctl restart snapd', I got http://paste.ubuntu.com/18690887/ and

$ systemctl status snapd -n 20
● snapd.service - Snappy daemon
   Loaded: loaded (/lib/systemd/system/snapd.service; enabled; vendor preset: enabled)
   Active: inactive (dead) (Result: exit-code) since Thu 2016-07-07 17:31:44 CST; 6min ago
  Process: 2266 ExecStart=/usr/lib/snapd/snapd (code=exited, status=2)
 Main PID: 2266 (code=exited, status=2)

Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: snapd.service: Unit entered failed state.
Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: snapd.service: Failed with result 'exit-code'.
Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: snapd.service: Service hold-off time over, scheduling restart.
Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: Stopped Snappy daemon.
Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: snapd.service: Start request repeated too quickly.
Jul 07 17:31:44 ThinkPad-X1-Carbon systemd[1]: Failed to start Snappy daemon.

[Anthony Wong (anthonywong)]

To my despair, I reset everything with zyga's reset-state script.

[Anthony Wong (anthonywong)]

`snap disconnect ubuntu-core:camera` can always reproduce this issue.

[Zygmunt Krynicki (zyga)]

This is a duplicate of the connect/disconnect UX and corresponding fix to the abbreviated syntax behavior.

[Gustavo Niemeyer (niemeyer)]

This is not just UX. There's an actual panic in doDisconnect. No UX issue should result in a panic.

[Zygmunt Krynicki (zyga)]

Yes, I agree, this was a mental shortcut. It started long ago as a fix for the panic and evolved into UX change

[Michael Vogt (mvo)]

Fixed according to zyga