Hey everyone, I just wanted to share my recent experience with updating my Home Assistant setup. After upgrading to Home Assistant OS 6.5, I encountered some unexpected issues. Specifically, I started getting errors like ‘Failed to call service switch/turn_on. Service not found’ when trying to control my lights and switches. At first, I was a bit puzzled because everything had been working perfectly before the update.
I decided to dive into the problem and started by checking my configurations. I realized that the way I had integrated my second Home Assistant instance (running Zigbee2mqtt/mqtt) into the main setup might have been affected by the update. After some research and troubleshooting, I discovered that the service calls were not being properly routed between the instances anymore.
I reached out to the community for help, and to my relief, someone suggested adjusting the entity configuration and ensuring that the services were correctly exposed. Following their advice, I made a few tweaks to my setup, and voilà! Everything started working again smoothly.
This experience taught me the importance of keeping configurations up to date, especially after major updates. It also reminded me of how invaluable the Home Assistant community is. I’m really grateful to everyone who contributed to solving this issue and making my smart home fully functional again. 
If anyone else is facing similar problems after an update, don’t hesitate to reach out for help. The community is always here to assist, and there’s usually a solution just a few clicks away! 