Installation fails when running: $ sudo snap install hello-world error: cannot perform the following tasks: - Mount snap "core" (11420) (cannot run unsquashfs: ----- Parallel unsquashfs: Using 16 processors 1 inodes (1 blocks) to write /tmp/read-file859363692/unpack /tmp/read-file859363692/unpack/meta /tmp/read-file859363692/unpack/meta/snap.yaml created 1 files created 2 directories created 0 symlinks created 0 devices created 0 fifos created 0 sockets -----) Reproducible: Always Steps to Reproduce: 1. Configure kernel with additional CONFIG_* options for snapd. 2. Install and configure apparmor, enable at boot 3 emerge --ask app-emulation/snapd 4. systemctl enable --now snapd 5. systemctl enable --now snapd.socket 6. systemctl enable --now snapd.apparmor 3. sudo snap install hello-world Actual Results: Journald has some more details about the problem: $ journalctl Aug 02 00:54:24 toster snapd[102083]: api_snaps.go:299: Installing snap "hello-world" revision unset Aug 02 00:54:28 toster snapd[102083]: store_download.go:482: Download size for https://api.snapcraft.io/api/v1/snaps/download/99T7MUlRhtI3U0QFgl5mXXESAiSwt776_ 11420.snap: 104210432 Aug 02 00:54:40 toster snapd[102083]: taskrunner.go:271: [change 7 "Mount snap \"core\" (11420)" task] failed: cannot run unsquashfs: Aug 02 00:54:40 toster snapd[102083]: ----- Aug 02 00:54:40 toster snapd[102083]: Parallel unsquashfs: Using 16 processors Aug 02 00:54:40 toster snapd[102083]: 1 inodes (1 blocks) to write Aug 02 00:54:40 toster snapd[102083]: /tmp/read-file859363692/unpack Aug 02 00:54:40 toster snapd[102083]: /tmp/read-file859363692/unpack/meta Aug 02 00:54:40 toster snapd[102083]: /tmp/read-file859363692/unpack/meta/snap.yaml Aug 02 00:54:40 toster snapd[102083]: created 1 files Aug 02 00:54:40 toster snapd[102083]: created 2 directories Aug 02 00:54:40 toster snapd[102083]: created 0 symlinks Aug 02 00:54:40 toster snapd[102083]: created 0 devices Aug 02 00:54:40 toster snapd[102083]: created 0 fifos Aug 02 00:54:40 toster snapd[102083]: created 0 sockets Aug 02 00:54:40 toster snapd[102083]: ----- Aug 02 00:54:40 toster systemd[1]: Cannot find unit for notify message of PID 102179, ignoring. Aug 02 00:54:42 toster snapd[102083]: handlers.go:511: Reported install problem for "core" as 668ec444-f2d8-11eb-aa83-fa163e983629 OOPSID I added NotifyAccess=all to /usr/lib/systemd/user/snapd.session-agent.service before that I was getting: Aug 02 00:58:42 toster systemd[1]: snapd.service: Got notification message from PID 103319, but reception only permitted for main PID 102083 Expected Results: Successful installation of snap. Relevant package versions and useflags: [ebuild R ] sys-libs/libseccomp-2.5.1::gentoo USE="static-libs -python" ABI_X86="(64) -32 (-x32)" PYTHON_TARGETS="python3_9 -python3_8" 0 KiB [ebuild R ] sys-apps/systemd-248.6:0/2::gentoo USE="apparmor cgroup-hybrid gcrypt hwdb kmod lz4 lzma pam pcre (policykit) resolvconf seccomp (split-usr) sysv-utils zstd -acl -audit -build -cryptsetup -curl -dns-over-tls -elfutils -gnuefi -homed -http -idn -importd -nat -pkcs11 -pwquality -qrcode -repart (-selinux) -static-libs -test -tpm -vanilla -xkb" ABI_X86="(64) -32 (-x32)" 0 KiB [ebuild R ~] sys-apps/apparmor-3.0.1::gentoo USE="-doc" 0 KiB [ebuild R ~] app-emulation/snapd-2.51::gentoo USE="apparmor cgroup-hybrid gtk kde systemd forced-devmode" 0 KiB No warnings about missing kernel CONFIG_* options during snapd installation, active kernel has CONFIG_CGROUP_DEVICE CONFIG_CGROUP_FREEZER CONFIG_SQUASHFS_LZO CONFIG_SQUASHFS_XZ, etc $ cat /proc/cmdline BOOT_IMAGE=/vmlinuz-5.4.134-gentoo-x86_64 [redacted] apparmor=1 security=apparmor
