Migration from 1.8 to newest(stable) OpenHAB release

[rossko57]

@Artyom_Syomushkin

does MQTT 2.4.0 support command and event bus binding like in 1.8, so that all events are published and subscribed?

No.
You may retain MQTT 1.x for this purpose or

Marketplace MQTT Event Bus

Update: Complete rewrite to use the rule templates published to the Marketplace. There is no need to code this or copy/paste code to make this work. There is a Remote openHAB binding which replaces this capability in most cases. See openhab-addons/bundles/org.openhab.binding.remoteopenhab at main · openhab/openhab-addons · GitHub . However there may be use cases where MQTT is preferred, such as integration with a non-openHAB service. Introduction What’s an Event Bus? There are times when one…