I dug a little deeper, it appears that calling 2 http APIs in parallel results in vyos-http-api library crash.
Jul 5 08:47:39 cxr vyos-http-api[107198]: Configuration modified via HTTP API using key 'ccube-dev' Jul 5 08:47:39 cxr vyos-http-api[107198]: INFO: None:0 - "POST /configure HTTP/1.0" 200 OK Jul 5 08:47:39 cxr netplugd[907]: br4: can't get flags: No such device Jul 5 08:47:39 cxr vyos-http-api[107198]: processing form data Jul 5 08:47:39 cxr netplugd[907]: br4: can't get flags: No such device Jul 5 08:47:39 cxr netplugd[907]: message repeated 3 times: [ br4: can't get flags: No such device] Jul 5 08:47:39 cxr netplugd[907]: br5: can't get flags: No such device Jul 5 08:47:39 cxr netplugd[907]: br4: can't get flags: No such device Jul 5 08:47:39 cxr netplugd[907]: message repeated 27 times: [ br4: can't get flags: No such device] Jul 5 08:47:40 cxr vyos-http-api[107198]: INFO: None:0 - "POST /config-file HTTP/1.0" 200 OK Jul 5 08:47:40 cxr vyos-http-api[107198]: processing form data Jul 5 08:47:40 cxr vyos-http-api[107198]: INFO: None:0 - "POST /retrieve HTTP/1.0" 400 Bad Request Jul 5 08:47:40 cxr vyos-http-api[107198]: processing form data Jul 5 08:47:40 cxr vyos-http-api[107198]: processing form data Jul 5 08:47:40 cxr ntpd[3893]: Listen normally on 87 vti1 169.254.231.46:123 Jul 5 08:47:40 cxr ntpd[3893]: new interface(s) found: waking up resolver Jul 5 08:47:41 cxr kernel: [104872.825731] vyos-http-api-s[107280]: segfault at 1020 ip 00007f792d30391d sp 00007f792dce93e0 error 4 in libvyosconfig.so.0[7f792d2ae000+10c000] Jul 5 08:47:41 cxr kernel: [104872.825745] Code: 20 48 83 c4 08 c3 e8 f2 d9 fa ff eb c6 48 83 ec 48 48 8b 40 10 48 89 44 24 18 48 8b 40 20 48 8b 58 20 48 8b 5b 20 48 8b 7b 20 <48> 8b 77 20 48 89 74 24 10 48 8b 56 20 48 89 54 24 20 48 8b 7f 08 Jul 5 08:47:41 cxr kernel: [104872.833057] net_ratelimit: 24 callbacks suppressed Jul 5 08:47:41 cxr kernel: [104872.833059] IPv4: martian source 10.10.10.18 from 10.10.10.1, on dev eth2 Jul 5 08:47:41 cxr kernel: [104872.833061] ll header: 00000000: ff ff ff ff ff ff 6a 2c d7 cd 51 fd 08 06 Jul 5 08:47:41 cxr systemd[1]: vyos-http-api.service: Main process exited, code=killed, status=11/SEGV