@tjkreidl which host? Enabling HA on other pools doesn't trigger any host reboot.
Enabling HA on this pool results in "Internal_Error(Not_found)"
I am aware that a host reboots when you remove it from a compute pool but that is something separate.

@tjkreidl ntp is synchronized across all the hosts. All the hosts can reach each other and are in a pool already. There are even vms running properly on the said compute. The only thing not working is enabling HA.

@olivierlambert Yes. xe vm-list shows all the running vms on the pool

@olivierlambert Notable error on that compute is that it can't find the UUID of the pool master, for some reason.

Mar 13 14:12:00 compute-04 xapi: [error||16119 HTTPS 172.21.17.96->:::80|host.ha_join_liveset R:c44ae729771f|xapi_ha] Failed to find the UUID address of host with address 172.21.18.96
Mar 13 14:12:00 compute-04 xapi: [error||16119 :::80||backtrace] host.ha_join_liveset R:c44ae729771f failed with exception Not_found
Mar 13 14:12:00 compute-04 xapi: [error||16119 :::80||backtrace] 1/12 xapi Raised at file hashtbl.ml, line 194

172.21.17.96 is the management IP of the pool master(compute-01) while 172.21.18.96 is the IP for the same host, used as a Storage interface.

@olivierlambert The pool is showing all hosts as connected, same for all the shared SRs. There are even vms running on the new compute host. Only thing not working is enabling HA.
One of the SRs is showing that HA is configured. Should that be the case when HA is not enabled yet?

@olivierlambert I added a compute to the pool. It added successfully but HA won't come up.

@Denson I also have a shared NFS SR already configured on the pool.

Hi everyone,
I've encountered an issue i've never seen before where trying to enable HA on a compute pool fails with the error "INTERNAL_ERROR(Not_found). NTP is enabled on all the computes and all the computes are already in a pool. I have updated all the hosts in the pool, just to rule out a pending update but no change.
Below is the log output from the xensource log file from the poolmaster.

Mar 12 15:56:49 compute-01 xapi: [error||472789 /var/lib/xcp/xapi||backtrace] host.ha_join_liveset R:aa412db4d158 failed with exception Server_error(INTERNAL_ERROR, [ Not_found ])
Mar 12 15:57:04 compute-01 xapi: [error||472469 HTTPS 172.28.18.83->:::80|pool.enable_ha R:c2beab627da0|xapi_ha] Caught exception while calling Host.ha_join_liveset: 'compute-04' ('OpaqueRef:07de98bb-5cf2-4cd4-bda6-becbc843f413') INTERNAL_ERROR: [ Not_found ]
Mar 12 15:57:04 compute-01 xapi: [error||472469 HTTPS 172.28.18.83->:::80|pool.enable_ha R:c2beab627da0|xapi_ha] Attempting to disable HA pool-wide
Mar 12 15:57:04 compute-01 xapi: [debug||472469 HTTPS 172.28.18.83->:::80|pool.enable_ha R:c2beab627da0|xapi_ha] Disabling HA on the Pool
Mar 12 15:57:04 compute-01 xapi: [debug||472469 :::80||xapi_ha] Disabling HA, so also disabling writing to redo-log
Mar 12 15:57:04 compute-01 xapi: [debug||472469 :::80||helpers] about to call script: /usr/libexec/xapi/cluster-stack/xhad/ha_query_liveset
Mar 12 15:57:11 compute-01 xapi: [debug||472469 :::80||xapi_ha] Caught exception while enabling HA: INTERNAL_ERROR: [ Not_found ]
Mar 12 15:57:11 compute-01 xapi: [error||472469 :::80||backtrace] pool.enable_ha R:c2beab627da0 failed with exception Server_error(INTERNAL_ERROR, [ Not_found ])
Mar 12 15:57:11 compute-01 xapi: [error||472469 :::80||backtrace] 1/14 xapi Raised at file ocaml/xapi/xapi_ha.ml, line 1972
Mar 12 15:57:11 compute-01 xapi: [error||472469 :::80||backtrace] 4/14 xapi Called from file ocaml/xapi/xapi_ha.ml, line 1918
Mar 12 15:57:11 compute-01 xapi: [error||472469 :::80||backtrace] 5/14 xapi Called from file ocaml/xapi/xapi_ha.ml, line 2026

If anyone has any pointers on how to resolve this, it would be appreciated.
2025-03-12T12_57_11.614Z - XO.txt

@stormi It was a fresh install of 8.2.1. No updates had been applied.

@ThasianXi This worked well, thank you for the feedback!