Trying to load balance a node other node has started calling missing CAN_INSTALL in config foler

I was preparing to setup load balance 2 nodes, but even before I can reach that stage, I started getting error message saying


It looks like you are trying to reinstall your Nextcloud. However the file CAN_INSTALL is missing from your config directory. Please create the file CAN_INSTALL in your config folder to continue.

but when I earlier synced the nextcloud to a remote node and maraidb db replciaiton.
I didn t got this error message.

what am I missing here. I do not want to setup new install just a duplicate node.
that also has duplicated data folder.

Nextcloud version: 20.1.1
Operating system and version: Ubuntu 20.04
Apache or nginx version (eg, Apache 2.4.25): Apache/2.4.41 (Ubuntu)
PHP version (eg, 7.1): 7.4