XCP-NG can’t add a Server to Pool

19th November 2025

Error: Unable to add host to pool (db mismatch)

Step1;
on each host run
yum update
when asked to confirm installing updates say Y
have done this many times on live hosts with no bad results. Schedule a weekend reboot of the host.

Step2; if step1 didn’t work
on each host in the pool run the following
xe host-list params=software-version

it will list the database version at the end, reboot the host with the oldest/mismatched DB version. (you may want to move the VMs off first)