pvesh set returns "malformed JSON string"


New Member
Oct 26, 2016
I trying to change LXC container (1166) description via pvesh utility and get error:

root@dp-nd03:~# pvesh  set /nodes/dp-nd07/lxc/1166/config  --description "check_description"
malformed JSON string, neither tag, array, object, number, string or atom, at character offset 0 (before "(end of string)") at /usr/share/perl5/PVE/CLI/pvesh.pm line 125.

but if I run the same command on the node where the container is running, it works without errors

root@dp-nd07:~# pvesh  set /nodes/dp-nd07/lxc/1166/config  --description "check_description"

Some info about pve version:

pveversion -v
proxmox-ve: 5.3-1 (running kernel: 4.15.18-9-pve)
pve-manager: 5.3-8 (running version: 5.3-8/2929af8e)
pve-kernel-4.15: 5.2-12
pve-kernel-4.15.18-9-pve: 4.15.18-30
pve-kernel-4.4.134-1-pve: 4.4.134-112
pve-kernel-4.4.67-1-pve: 4.4.67-92
pve-kernel-4.4.35-1-pve: 4.4.35-77
pve-kernel-4.4.19-1-pve: 4.4.19-66
corosync: 2.4.4-pve1
criu: 2.11.1-1~bpo90
glusterfs-client: 3.8.8-1
ksm-control-daemon: 1.2-2
libjs-extjs: 6.0.1-2
libpve-access-control: 5.1-3
libpve-apiclient-perl: 2.0-5
libpve-common-perl: 5.0-43
libpve-guest-common-perl: 2.0-19
libpve-http-server-perl: 2.0-11
libpve-storage-perl: 5.0-35
libqb0: 1.0.3-1~bpo9
lvm2: 2.02.168-pve6
lxc-pve: 3.1.0-1
lxcfs: 3.0.2-2
novnc-pve: 1.0.0-2
proxmox-widget-toolkit: 1.0-22
pve-cluster: 5.0-33
pve-container: 2.0-33
pve-docs: 5.3-1
pve-edk2-firmware: 1.20181023-1
pve-firewall: 3.0-16
pve-firmware: 2.0-6
pve-ha-manager: 2.0-6
pve-i18n: 1.0-9
pve-libspice-server1: 0.14.1-1
pve-qemu-kvm: 2.12.1-1
pve-xtermjs: 1.0-5
qemu-server: 5.0-44
smartmontools: 6.5+svn4324-1
spiceterm: 3.0-5
vncterm: 1.5-3

I think problem in proxy_handler function (i replaced empty string by $json = "{}" and the error disappeared) or in the
 --output-format json
which returned empty string

sub proxy_handler {
    my ($node, $remip, $path, $cmd, $param) = @_;

    my $args = [];
    foreach my $key (keys %$param) {
        next if $key eq 'quiet' || $key eq 'output-format'; # just to  be sure
        push @$args, "--$key", $param->{$key};

    my $remcmd = ['ssh', '-o', 'BatchMode=yes', "root\@$remip",
                  'pvesh', '--noproxy', $cmd, $path,
                  '--output-format', 'json'];

    if (scalar(@$args)) {
        my $cmdargs = [String::ShellQuote::shell_quote(@$args)];
        push @$remcmd, @$cmdargs;

    my $json = '';
    PVE::Tools::run_command($remcmd, errmsg => "proxy handler failed",
                            outfunc => sub { $json .= shift });

    return decode_json($json);


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