Hi @Alexd1985,
thank you for the quick feedback. I have not experienced the invalidity of the kes key either. I monitor its current state through a dashboard and that has always been enough. Having said that, my interest in this topic arose given the current “dry” period, during which my pool is minting far less than expected. This particular topic has been brought up here: Slot leader schedule & historical assignments So, @ADA-INDO’s post got me thinking: what if I have a problem with KES, VRF or CERT, which I cannot see?
Since then, I have looked through logs and have found 0 instances of assigned blocks (is_leader), so I guess I am not being assigned blocks to mint. Patience 
Back to the original question, what I meant was: if there is an issue with KES, VRF or CERT, the BP will throw an error on startup, right? Or am I missing something?
Cheers,
A
PS punctuation and grammar edits