zabbix_server [1950]: ERROR [file and function: <misc.c,deserialize_variant>, revision:68dc2b05cb, line:138] Something impossible has just happened.
  1950:20210914:184118.946 === Backtrace: ===
  1950:20210914:184118.947 14: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](zbx_backtrace+0x52) [0x55f65d5097d2]
  1950:20210914:184118.947 13: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](+0x22a832) [0x55f65d4f8832]
  1950:20210914:184118.947 12: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](zbx_eval_deserialize+0x17f) [0x55f65d4f8d00]
  1950:20210914:184118.947 11: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](zbx_eval_deserialize_dyn+0x67) [0x55f65d4f9c33]
  1950:20210914:184118.947 10: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](prepare_triggers+0x5a) [0x55f65d4dc1d5]
  1950:20210914:184118.947 9: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](+0x1b0825) [0x55f65d47e825]
  1950:20210914:184118.947 8: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](+0x1b44c5) [0x55f65d4824c5]
  1950:20210914:184118.947 7: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](zbx_sync_history_cache+0x8b) [0x55f65d483021]
  1950:20210914:184118.947 6: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](dbsyncer_thread+0x236) [0x55f65d338b2f]
  1950:20210914:184118.947 5: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](zbx_thread_start+0x3b) [0x55f65d51ad17]
  1950:20210914:184118.947 4: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](MAIN_ZABBIX_ENTRY+0xe4b) [0x55f65d325a9d]
  1950:20210914:184118.947 3: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](daemon_start+0x303) [0x55f65d509314]
  1950:20210914:184118.947 2: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](main+0x309) [0x55f65d324b34]
  1950:20210914:184118.947 1: /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf3) [0x7fc7dcac40b3]
  1950:20210914:184118.947 0: /usr/sbin/zabbix_server: history syncer #8 [processed 0 values, 0 triggers in 0.000042 sec, syncing history](_start+0x2e) [0x55f65d32394e]
[..]
   622:20210914:184119.008 One child process died (PID:1950,exitcode/signal:1). Exiting ...
   622:20210914:184119.726 syncing history data...
   622:20210914:184119.785 syncing history data... 88.565022%
   622:20210914:184119.785 syncing history data... 88.565022%
   622:20210914:184119.785 syncing history data... 88.565022%
   622:20210914:184119.785 syncing history data... 88.565022%
  *endlessly repeating*