Ayeee this is it, sorry i forgot to tell that i was able to implement the active check successfully thanks you all!
another note i found this handy tutorial here too:
https://www.steinkogler.org/2016/08/21/check-mk-write-your-own-active-check/
but i have one more question, sorry i’m asking too much but i’m used to custom scripts, but not this active checks, okay the error is gone using your suggestion, but i have another problem, how do i debug this to check how to check is behaving and fix what is required, on normal checks i used cmk -nv --debug /check_esim_profile--detect-plugins={{check_name}} {{sitename}}' i tried to do the same here cmk -nv --debug --detect-plugins=esim_profile CheckMK_MontyHolding but i’m not getting any response from the print instructions.