on the new node take a backup of /etc/pve/nodes/YOURNEWNODENAME/qemu-server and delete all the files in it and try to join the server once done restore the file to original location, it worked for me!
- NewNode: cp -rpf /etc/pve/nodes/YOURNEWNODENAME/qemu-server /root/
- NewNode: rm -rf /etc/pve/nodes/YOURNEWNODENAME/qemu-server/*
- OldNode: get the “Join Information” from your main
- NewNode: click on “Join Cluster” and add the info copied earlier and join the cluster
- NewNode: cp -rpf /root/qemu-server /etc/pve/nodes/YOURNEWNODENAME/
and you are done! just Make sure you have no conflicting VM / LXC IDs.