On Debian 9.0 with snapd 2.27.4-1 installing castersoundboard 0+git.647f784 rev 21 goes ok, but running it fails.
castersoundboard
cannot locate the base snap: ubuntu-core: No such file or directory
However ubuntu-core is deprecated.
snap install ubuntu-core
error: cannot install "ubuntu-core", please use "core" instead
Please update dependencies.
Thanks.
You may want to file an issue on Castersoundboard’s GitHub here (and then link to your Issue here) but it seems to be @wimpress who made this snap so he may have an idea of how to fix this 
Can you try the edge snap to see if that works (use sudo snap refresh castersoundboard --edge)?
Nope. Still the same.
snap list Name Version Rev Developer Notes castersoundboard 0+git.c41a4f2 34 rikai - core 16-2.26.14 2462 canonical core,devmode
castersoundboard cannot locate the base snap: ubuntu-core: No such file or directory
This looks like a regression related to the recently introduced base snaps (at least, the initial support). Let us look at reproducing the issue and getting back to you.
On Debian 9 I cannot reproduce the issue. Note that I have snapd 2.21 from the stable debian package and snapd 2.27.5 from the core snap.
I will try with Debian sid next, can you please run snap version and add the result here?
You may want to file an issue on Castersoundboard’s GitHub here (and then link to your Issue here) but it seems to be @wimpress who made this snap so he may have an idea of how to fix this
Hehe… it was Wimpy who told me to post it here last night. 
Said it needed greater minds to be engaged. From what I gather though it is not isolated to castersoundboard snap. As you might also see on the thread about warzone2100 and Krita something is falling back to the legacy ubuntu-core dependency even though that was deprecated a few months back.
Is there some way to audit the listed snaps to see if any contain impossible build dependencies. What I find irritating is they install fine so don’t complain about dependencies then. But they fail to run requiring ubuntu-core.
A little odd, don’t you think?
Anyway, not that their is anything I can particularly do about it as it will need to be fixed further upstream but seems there is a lack of clarity over the issue which some snap maintainers might not realise as being important.
Thanks.
Again, just to recap: no snap depends on ubuntu-core specifically. This looks like a regression affection certain systems. Can anyone affected please add their snap version here.
So on Debian sid with snapd 2.27.4-1 (oddly there’s no reexec, I need to check it out separately) everything works correctly.
Thanks a lot for your posting! Could you please paste the output of the following two commands here?
$ snap version
and
$ snap list
thanks you!
snap version snap 2.27.4-1 snapd 2.27.4-1 series 16 debian unknown kernel 4.12.0-1-amd64
and
snap list Name Version Rev Developer Notes castersoundboard 0+git.c41a4f2 34 rikai - core 16-2.26.14 2462 canonical core,devmode krita 3.2.0 26 krita - warzone2100 3.2.3 5 diddledan -
Can you please pastebin /snap/*/*/meta/snap.yaml - that is, all the snap.yaml files you have in /snap
Hmm, all of the data looks correct. I’ll look at possible bugs in the source that would explain this.
Would explain why other apps seem broken. The Warzone2100 one was compiled only last night though which makes it as fresh as it can be.
Hey ho.
I have a theory I’d like to confirm with you. Can you please run and paste:
ls -l /snap/core/
ls -l /snap/core/ total 0 drwxr-xr-x 24 root root 321 Jul 20 13:45 2462
So you don’t have anything (not even mount points) there and yet somehow snap list shows that you have a core snap. Can you please pastebin /proc/self/mountinfo as well as tell us if you are using some kind of container technology? Can you look at your journalctl output and also paste snap changes for further analysis.
cat /proc/self/mountinfo 18 24 0:18 / /sys rw,nosuid,nodev,noexec,relatime shared:7 - sysfs sysfs rw 19 24 0:4 / /proc rw,nosuid,nodev,noexec,relatime shared:14 - proc proc rw 20 24 0:6 / /dev rw,nosuid,relatime shared:2 - devtmpfs udev rw,size=16332732k,nr_inodes=4083183,mode=755 21 20 0:19 / /dev/pts rw,nosuid,noexec,relatime shared:3 - devpts devpts rw,gid=5,mode=620,ptmxmode=000 22 24 0:20 / /run rw,nosuid,noexec,relatime shared:5 - tmpfs tmpfs rw,size=3270744k,mode=755 24 0 254:11 / / rw,relatime shared:1 - ext4 /dev/mapper/kratoforn–vg-root rw,errors=remount-ro,data=ordered 25 18 0:7 / /sys/kernel/security rw,nosuid,nodev,noexec,relatime shared:8 - securityfs securityfs rw 26 20 0:22 / /dev/shm rw,nosuid,nodev shared:4 - tmpfs tmpfs rw 27 22 0:23 / /run/lock rw,nosuid,nodev,noexec,relatime shared:6 - tmpfs tmpfs rw,size=5120k 28 18 0:24 / /sys/fs/cgroup ro,nosuid,nodev,noexec shared:9 - tmpfs tmpfs ro,mode=755 29 28 0:25 / /sys/fs/cgroup/unified rw,nosuid,nodev,noexec,relatime shared:10 - cgroup2 cgroup rw 30 28 0:26 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime shared:11 - cgroup cgroup rw,xattr,name=systemd 31 18 0:27 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:12 - pstore pstore rw 32 18 0:28 / /sys/firmware/efi/efivars rw,nosuid,nodev,noexec,relatime shared:13 - efivarfs efivarfs rw 33 28 0:29 / /sys/fs/cgroup/cpu,cpuacct rw,nosuid,nodev,noexec,relatime shared:15 - cgroup cgroup rw,cpu,cpuacct 34 28 0:30 / /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,perf_event 35 28 0:31 / /sys/fs/cgroup/net_cls,net_prio rw,nosuid,nodev,noexec,relatime shared:17 - cgroup cgroup rw,net_cls,net_prio 36 28 0:32 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime shared:18 - cgroup cgroup rw,blkio 37 28 0:33 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime shared:19 - cgroup cgroup rw,freezer 38 28 0:34 / /sys/fs/cgroup/pids rw,nosuid,nodev,noexec,relatime shared:20 - cgroup cgroup rw,pids 39 28 0:35 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,memory 40 28 0:36 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime shared:22 - cgroup cgroup rw,devices 41 28 0:37 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime shared:23 - cgroup cgroup rw,cpuset 42 19 0:38 / /proc/sys/fs/binfmt_misc rw,relatime shared:24 - autofs systemd-1 rw,fd=28,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=2324 43 20 0:17 / /dev/mqueue rw,relatime shared:25 - mqueue mqueue rw 45 18 0:8 / /sys/kernel/debug rw,relatime shared:26 - debugfs debugfs rw 44 20 0:39 / /dev/hugepages rw,relatime shared:27 - hugetlbfs hugetlbfs rw 46 22 0:40 / /run/rpc_pipefs rw,relatime shared:28 - rpc_pipefs sunrpc rw 78 24 7:2 / /snap/krita/25 ro,nodev,relatime shared:29 - squashfs /dev/loop2 ro 76 24 7:0 / /snap/core/2462 rw,relatime shared:30 - squashfs /dev/loop0 ro 77 24 7:1 / /snap/warzone2100/5 ro,nodev,relatime shared:31 - squashfs /dev/loop1 ro 82 24 7:3 / /snap/castersoundboard/34 ro,nodev,relatime shared:32 - squashfs /dev/loop3 ro 84 24 7:4 / /snap/krita/26 ro,nodev,relatime shared:33 - squashfs /dev/loop4 ro 86 24 7:5 / /snap/castersoundboard/21 rw,relatime shared:34 - squashfs /dev/loop5 ro 88 24 259:2 / /boot rw,relatime shared:35 - ext2 /dev/nvme0n1p2 rw,block_validity,barrier,user_xattr,acl 90 88 259:1 / /boot/efi rw,relatime shared:36 - vfat /dev/nvme0n1p1 rw,fmask=0077,dmask=0077,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro 92 24 0:41 / /home rw,relatime shared:37 - btrfs /dev/mapper/kratoforn–vg-home rw,ssd,space_cache,subvolid=5,subvol=/ 94 24 254:1 / /usr/src rw,relatime shared:38 - xfs /dev/mapper/vg_ssd-src rw,attr2,inode64,noquota 95 24 254:2 / /mnt/WinGame rw,relatime shared:39 - xfs /dev/mapper/vg_ssd-WinGame rw,attr2,inode64,noquota 98 94 254:0 / /usr/src/git rw,relatime shared:40 - xfs /dev/mapper/vg_ssd-git rw,attr2,inode64,noquota 100 42 0:44 / /proc/sys/fs/binfmt_misc rw,relatime shared:41 - binfmt_misc binfmt_misc rw 502 22 0:50 / /run/user/120 rw,nosuid,nodev,relatime shared:390 - tmpfs tmpfs rw,size=3270740k,mode=700,uid=120,gid=125 458 24 254:7 / /var/lib/libvirt/images/Kali-store rw,relatime shared:399 - xfs /dev/mapper/vg_ssd-Kali–store rw,attr2,inode64,noquota 536 22 0:51 / /run/user/1000 rw,nosuid,nodev,relatime shared:465 - tmpfs tmpfs rw,size=3270740k,mode=700,uid=1000,gid=1000 548 536 0:53 / /run/user/1000/gvfs rw,nosuid,nodev,relatime shared:475 - fuse.gvfsd-fuse gvfsd-fuse rw,user_id=1000,group_id=1000 559 18 0:52 / /sys/fs/fuse/connections rw,relatime shared:485 - fusectl fusectl rw 571 24 0:57 / /keybase rw,nosuid,nodev,relatime shared:494 - fuse /dev/fuse rw,user_id=1000,group_id=1000 308 22 0:20 /snapd/ns /run/snapd/ns rw,nosuid,noexec,relatime - tmpfs tmpfs rw,size=3270744k,mode=755 320 92 0:46 / /home/user/mnt/veritanuda@gd rw,nosuid,nodev,relatime shared:292 - fuse.google-drive-ocamlfuse google-drive-ocamlfuse rw,user_id=1000,group_id=1000
So you have the core snap mounted on /snap/core/2462 but /snap/core is empty. Something very curious must have happened there.