Seccomp error when starting transmission

OpenWrt r19337, Linksys WRT1900AC v1
I get this error when starting transmission:

Wed Apr 13 22:50:57 2022 user.notice transmission: Starting with 123932000 virt mem
Wed Apr 13 22:50:58 2022 user.err : jail: seccomp: no default action set
Wed Apr 13 22:50:58 2022 user.err : jail: /usr/bin/transmission-daemon: failed to parse seccomp filter rules /etc/seccomp/transmission-daemon.json
Wed Apr 13 22:50:58 2022 daemon.err transmission-daemon[22357]: jail: seccomp: no default action set
Wed Apr 13 22:50:58 2022 daemon.err transmission-daemon[22357]: jail: /usr/bin/transmission-daemon: failed to parse seccomp filter rules /etc/seccomp/transmission-daemon.json
Wed Apr 13 22:50:58 2022 daemon.info procd: Instance transmission::instance1 s in a crash loop 8 crashes, 0 seconds since last crash

seccomp is enabled in kernel.

Is this a bug?

Are there filter rules in there ?

It's a long json.

{
        "whitelist": [
                "accept",
                "accept4",
                [...]
                "write",
                "writev"
        ],
        "policy": 1
}

What about the permissions? usually if you start transmission as root/manually, the files get wrong auths.

Trying to solve the issue, I built transmission from git master instead of downloading it with opkg from OpenWrt servers. Problem solved. The file looks very different now:

{
        "defaultAction": "SCMP_ACT_KILL_PROCESS",
        "syscalls": [
                {
                        "names": [
                                "accept",
                                "accept4",
                                ...
                                "write",
                                "writev"
                        ],
                        "action": "SCMP_ACT_ALLOW"
                }
        ]
}

New version is "transmission-daemon - 3.00-18"
Old version is "transmission-daemon-openssl - 2.94-15"
There is probably something wrong with the old file or maybe the seccomp in newer kernel?