Cannot remove snaps on Ubuntu 21.04

snapd
1

I’m running an upgraded 21.04, not a fresh install, and had snaps installed prior to upgrade. I cannot remove any snaps from the system, always getting the same error message:

ERROR cannot remove snap file "chromium", will retry in 3 mins: incorrect number of tail fields, expected 3 but found 4

I can install them fine, but had troubles running Chromium (and others) until I figured out it works if I connect them to gnome-3-28-1804.

david@bulldog:~$ snap version
snap    2.49.2+git1056.g68bd611
snapd   2.49.2+git1056.g68bd611
series  16
ubuntu  21.04
kernel  5.11.0-13-generic

I’m not very savvy when it comes to snaps, so just let me know what you need.

Thanks in advance!

2

looks like you are using the edge channel of snapd … better do a

snap refresh --stable snapd

to get back to a non-development version

3

All right, I did, but the problem remains. I initially upgraded cause I thought maybe it would fix the problem.

david@bulldog:~$ sudo snap refresh --stable snapd
2021-04-04T21:23:24+03:00 INFO Waiting for automatic snapd restart...
snapd 2.49.1 from Canonical✓ refreshed
david@bulldog:~$ sudo snap remove vobsub2srt
2021-04-04T21:23:43+03:00 ERROR cannot remove snap file "vobsub2srt", will retry in 3 mins: incorrect number of tail fields, expected 3 but found 4
4

Can you attach the output of cat /proc/self/mountinfo ?

5

Certainly.

david@bulldog:~$ cat /proc/self/mountinfo
23 28 0:21 / /sys rw,nosuid,nodev,noexec,relatime shared:7 - sysfs sysfs rw
24 28 0:22 / /proc rw,nosuid,nodev,noexec,relatime shared:15 - proc proc rw
25 28 0:5 / /dev rw,nosuid,noexec,relatime shared:2 - devtmpfs udev rw,size=3993484k,nr_inodes=998371,mode=755,inode64
26 25 0:23 / /dev/pts rw,nosuid,noexec,relatime shared:3 - devpts devpts rw,gid=5,mode=620,ptmxmode=000
27 28 0:24 / /run rw,nosuid,nodev,noexec,relatime shared:5 - tmpfs tmpfs rw,size=805308k,mode=755,inode64
28 1 8:2 / / rw,relatime shared:1 - ext4 /dev/sda2 rw,errors=remount-ro
29 23 0:6 / /sys/kernel/security rw,nosuid,nodev,noexec,relatime shared:8 - securityfs securityfs rw
30 25 0:25 / /dev/shm rw,nosuid,nodev shared:4 - tmpfs tmpfs rw,inode64
31 27 0:26 / /run/lock rw,nosuid,nodev,noexec,relatime shared:6 - tmpfs tmpfs rw,size=5120k,inode64
32 23 0:27 / /sys/fs/cgroup ro,nosuid,nodev,noexec shared:9 - tmpfs tmpfs ro,size=4096k,nr_inodes=1024,mode=755,inode64
33 32 0:28 / /sys/fs/cgroup/unified rw,nosuid,nodev,noexec,relatime shared:10 - cgroup2 cgroup2 rw,nsdelegate
34 32 0:29 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime shared:11 - cgroup cgroup rw,xattr,name=systemd
35 23 0:30 / /sys/fs/pstore rw,nosuid,nodev,noexec,relatime shared:12 - pstore pstore rw
36 23 0:31 / /sys/firmware/efi/efivars rw,nosuid,nodev,noexec,relatime shared:13 - efivarfs efivarfs rw
37 23 0:32 / /sys/fs/bpf rw,nosuid,nodev,noexec,relatime shared:14 - bpf none rw,mode=700
38 32 0:33 / /sys/fs/cgroup/rdma rw,nosuid,nodev,noexec,relatime shared:16 - cgroup cgroup rw,rdma
39 32 0:34 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime shared:17 - cgroup cgroup rw,cpuset
40 32 0:35 / /sys/fs/cgroup/hugetlb rw,nosuid,nodev,noexec,relatime shared:18 - cgroup cgroup rw,hugetlb
41 32 0:36 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime shared:19 - cgroup cgroup rw,blkio
42 32 0:37 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime shared:20 - cgroup cgroup rw,devices
43 32 0:38 / /sys/fs/cgroup/cpu,cpuacct rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,cpu,cpuacct
44 32 0:39 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime shared:22 - cgroup cgroup rw,memory
45 32 0:40 / /sys/fs/cgroup/net_cls,net_prio rw,nosuid,nodev,noexec,relatime shared:23 - cgroup cgroup rw,net_cls,net_prio
46 32 0:41 / /sys/fs/cgroup/pids rw,nosuid,nodev,noexec,relatime shared:24 - cgroup cgroup rw,pids
47 32 0:42 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime shared:25 - cgroup cgroup rw,freezer
48 32 0:43 / /sys/fs/cgroup/perf_event rw,nosuid,nodev,noexec,relatime shared:26 - cgroup cgroup rw,perf_event
49 24 0:44 / /proc/sys/fs/binfmt_misc rw,relatime shared:27 - autofs systemd-1 rw,fd=29,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=18023
50 25 0:45 / /dev/hugepages rw,relatime shared:28 - hugetlbfs hugetlbfs rw,pagesize=2M
51 25 0:19 / /dev/mqueue rw,nosuid,nodev,noexec,relatime shared:29 - mqueue mqueue rw
52 23 0:7 / /sys/kernel/debug rw,nosuid,nodev,noexec,relatime shared:30 - debugfs debugfs rw
53 23 0:11 / /sys/kernel/tracing rw,nosuid,nodev,noexec,relatime shared:31 - tracefs tracefs rw
54 23 0:46 / /sys/fs/fuse/connections rw,nosuid,nodev,noexec,relatime shared:32 - fusectl fusectl rw
55 23 0:20 / /sys/kernel/config rw,nosuid,nodev,noexec,relatime shared:33 - configfs configfs rw
126 28 7:2 / /snap/chromium/1523 ro,nodev,relatime shared:70 - squashfs /dev/loop2 ro
129 28 7:4 / /snap/core/10908 ro,nodev,relatime shared:72 - squashfs /dev/loop4 ro
132 28 7:1 / /snap/chromium/1539 ro,nodev,relatime shared:74 - squashfs /dev/loop1 ro
135 28 7:3 / /snap/core/10859 ro,nodev,relatime shared:76 - squashfs /dev/loop3 ro
138 28 7:0 / /snap/chromium/1536 ro,nodev,relatime shared:78 - squashfs /dev/loop0 ro
141 28 7:5 / /snap/gnome-3-34-1804/66 ro,nodev,relatime shared:80 - squashfs /dev/loop5 ro
144 28 7:7 / /snap/core18/1997 ro,nodev,relatime shared:82 - squashfs /dev/loop7 ro
147 28 7:6 / /snap/discord/121 ro,nodev,relatime shared:84 - squashfs /dev/loop6 ro
150 28 7:8 / /snap/gnome-3-28-1804/145 ro,nodev,relatime shared:86 - squashfs /dev/loop8 ro
153 28 7:10 / /snap/discord/122 ro,nodev,relatime shared:88 - squashfs /dev/loop10 ro
156 28 7:9 / /snap/core/10958 ro,nodev,relatime shared:90 - squashfs /dev/loop9 ro
253 28 7:11 / /snap/snapd/11588 ro,nodev,relatime shared:92 - squashfs /dev/loop11 ro
257 28 7:12 / /snap/vlc/1700 ro,nodev,relatime shared:94 - squashfs /dev/loop12 ro
261 28 7:13 / /snap/gtk-common-themes/1514 ro,nodev,relatime shared:96 - squashfs /dev/loop13 ro
265 28 7:14 / /snap/gnome-3-26-1604/100 ro,nodev,relatime shared:98 - squashfs /dev/loop14 ro
269 28 7:15 / /snap/vlc/2103 ro,nodev,relatime shared:100 - squashfs /dev/loop15 ro
273 28 7:16 / /snap/gtk-common-themes/1513 ro,nodev,relatime shared:102 - squashfs /dev/loop16 ro
277 28 7:17 / /snap/snapd/11402 ro,nodev,relatime shared:104 - squashfs /dev/loop17 ro
159 28 7:18 / /snap/vobsub2srt/34 ro,nodev,relatime shared:106 - squashfs /dev/loop18 ro
160 28 7:20 / /snap/snap-store/518 ro,nodev,relatime shared:108 - squashfs /dev/loop20 ro
165 28 8:1 / /boot/efi rw,relatime shared:110 - vfat /dev/sda1 rw,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
168 28 7:19 / /snap/hello-world/29 ro,nodev,relatime shared:112 - squashfs /dev/loop19 ro
171 28 7:21 / /snap/core18/1988 ro,nodev,relatime shared:114 - squashfs /dev/loop21 ro
174 28 7:22 / /snap/gnome-3-28-1804/128 ro,nodev,relatime shared:116 - squashfs /dev/loop22 ro
177 28 7:23 / /snap/snap-store/498 ro,nodev,relatime shared:118 - squashfs /dev/loop23 ro
180 28 8:4 / /home rw,relatime shared:120 - ext4 /dev/sda4 rw
183 28 7:24 / /snap/gnome-3-34-1804/60 ro,nodev,relatime shared:122 - squashfs /dev/loop24 ro
186 28 7:25 / /snap/vobsub2srt/27 ro,nodev,relatime shared:124 - squashfs /dev/loop25 ro
189 28 7:26 / /snap/gnome-3-26-1604/98 ro,nodev,relatime shared:126 - squashfs /dev/loop26 ro
379 28 0:56 / /mnt/wd rw,relatime shared:704 - cifs //192.168.1.109/WD (USB) rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=132,noforcegid,addr=192.168.1.109,file_mode=0771,dir_mode=0771,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
398 28 0:57 / /mnt/data0 rw,relatime shared:714 - cifs //192.168.1.109/Public/data0 rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=132,noforcegid,addr=192.168.1.109,file_mode=0771,dir_mode=0771,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
417 28 0:58 / /mnt/data1 rw,relatime shared:724 - cifs //192.168.1.109/Public/data1 rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=132,noforcegid,addr=192.168.1.109,file_mode=0771,dir_mode=0771,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
436 28 0:59 / /mnt/censored rw,relatime shared:734 - cifs //192.168.1.109/censored/ rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=1000,noforcegid,addr=192.168.1.109,file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
455 27 0:60 / /run/user/1000 rw,nosuid,nodev,relatime shared:744 - tmpfs tmpfs rw,size=805304k,nr_inodes=201326,mode=700,uid=1000,gid=1000,inode64
475 455 0:61 / /run/user/1000/gvfs rw,nosuid,nodev,relatime shared:755 - fuse.gvfsd-fuse gvfsd-fuse rw,user_id=1000,group_id=1000
1416 28 0:62 / /var/lib/docker/overlay2/fc3a23bd9f178ab6d21da36ace958142f7203cf5eb0ee2c062c64ec4e1994d9c/merged rw,relatime shared:766 - overlay overlay rw,lowerdir=/var/lib/docker/overlay2/l/FKAWHKJVBVDFIJYA6LD5PNMUW3:/var/lib/docker/overlay2/l/DYBHKR6XIQG3G4V4D7ZSOGXO7F:/var/lib/docker/overlay2/l/CYQUKOGFJ4KG56MYVLTSXDBWFJ,upperdir=/var/lib/docker/overlay2/fc3a23bd9f178ab6d21da36ace958142f7203cf5eb0ee2c062c64ec4e1994d9c/diff,workdir=/var/lib/docker/overlay2/fc3a23bd9f178ab6d21da36ace958142f7203cf5eb0ee2c062c64ec4e1994d9c/work
1445 28 0:63 / /var/lib/docker/overlay2/c93d1a2da149dfa96bfdf4f3b836e5f6ae5ad323b0a21c15ed9822140d457f2a/merged rw,relatime shared:776 - overlay overlay rw,lowerdir=/var/lib/docker/overlay2/l/E2XLZWRHSOM37WAU2OPSUJ5N4O:/var/lib/docker/overlay2/l/UJTQEHU6SNZSAQCASVPSW5FHR4:/var/lib/docker/overlay2/l/LJM277O7JPH6F3JIG5ZPW3VIYJ:/var/lib/docker/overlay2/l/QCP76XQKVUYILVYSVIZI6QXNCJ:/var/lib/docker/overlay2/l/MW3222UOIYJ5TXVDJPTJQP4ZNW:/var/lib/docker/overlay2/l/LHUDAGWCCZ235XCAA7LJLQGKWM:/var/lib/docker/overlay2/l/V4SWEPKI73HBLKEFFWKGJI2DLK:/var/lib/docker/overlay2/l/BQWMKPXQJ4DHZWSIYDWG2MX52N:/var/lib/docker/overlay2/l/UOQS7JEACWOIIZSGJGIACKEQCQ:/var/lib/docker/overlay2/l/HGZUJH6OJBYNDOTQCVPS76GWQW,upperdir=/var/lib/docker/overlay2/c93d1a2da149dfa96bfdf4f3b836e5f6ae5ad323b0a21c15ed9822140d457f2a/diff,workdir=/var/lib/docker/overlay2/c93d1a2da149dfa96bfdf4f3b836e5f6ae5ad323b0a21c15ed9822140d457f2a/work
1661 27 0:4 net:[4026532526] /run/docker/netns/d2ff026ed99a rw shared:786 - nsfs nsfs rw
1682 27 0:4 net:[4026532585] /run/docker/netns/8bb01dd1b466 rw shared:796 - nsfs nsfs rw
1891 455 0:90 / /run/user/1000/doc rw,nosuid,nodev,relatime shared:968 - fuse.portal portal rw,user_id=1000,group_id=1000
6

AFAICT this looks like a bug in the kernel? You have this entry:

379 28 0:56 / /mnt/wd rw,relatime shared:704 
-
cifs //192.168.1.109/WD (USB)
rw,vers=3.0,cache=strict,username=censored,uid=1000,noforceuid,gid=132,noforcegid,addr=192.168.1.109,file_mode=0771,dir_mode=0771,soft,nounix,serverino,mapposix,rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1

The mountinfor should contain only 11 fields separated with whitespace, for this particular like there’s 12 fields. The manpage isn’t too informative:

The file contains lines of the form:

36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)

Specifically, the CIFS share name WD (USB) is what introduces an additional space. I don’t know why there is no quoting or the space hasn’t been replaced with %20 or some other encoding.

I think we may want to be less strict about parsing mountinfo. However it’s hard to tell bad input from a valid but quirky one. You can temporarily unmount the problematic share, at which point snap removal should be working again.

7

In my fstab it’s WD\040(USB), I suppose bash just prints the escaped char in my pastes.

Your suggestion works:

david@bulldog:~$ sudo umount /mnt/wd
david@bulldog:~$ sudo snap remove vobsub2srt
vobsub2srt removed

I’ll have to see if I can make my NAS export another volume name somehow.

Thanks for your help!

1 Like
8

I took a quick look at docker and podman. Both use the github.com/moby/sys/mountinfo package which has this workaround: https://github.com/moby/sys/blob/76d97006feb66cd237953a0df1e06648118cd101/mountinfo/mountinfo_linux.go#L60-L72

Looks like it’s a new thing available only in 5.11+ kernels, see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=653a5efb849aea1706648257c3c23ece82997f44

2 Likes
9

It’s been working fine for the past two, or so, Ubuntu releases and started when I upgraded to 21.04 with 5.11 kernel.

10

I’ve submitted a patch to the kernel which will be a part of 5.11.14 release. At some point the fix should be picked up by Ubuntu kernels too.

1 Like
11

HI! I’ve just got mine file and saw following line:

2260 190 0:311 / /Docker/host rw,noatime - 9p drvfs rw,dirsync,aname=drvfs;path=C:\Program Files\Docker\Docker\resources;symlinkroot=/mnt/,mmap,access=client,msize=262144,trans=virtio

can it be a reason that C:\Program Files\Docker\Docker\resources triggers parsing error because of the space inside?

1 Like
12

Had sth similar with a different snap. You may try to install Docker Desktop in a different location as mentioned here https://github.com/canonical/microk8s/issues/3911#issuecomment-1502879966