I was using this plugin: GitHub - michalskalski/cmk-apcupsd: Check-mk plugin for monitoring ups managed by apcupsd It doesn’t work anymore since I upgraded from 1.6.0p22 to 2.0.0, I tried reinstalling it but it always says in the UI that the check isn’t implemented. I supposed the syntax has change…

The plugin is very old and uses an syntax that was already deprecated since 1.4 or so. There is more needed than some minor changes. Complete rewrite would be a better description.