A lot of embedded hardware, financial transaction systems, factory critical ERP systems (I built one mid 90s in Clipper which is still running in that place; ac

A lot of embedded hardware, financial transaction systems, factory critical ERP systems (I built one mid 90s in Clipper which is still running in that place; actually I built a few which are still mission critical at this point in time). But, less hardcore, also my own projects; picturepush.com and flexlists.com for instance have been running for > 10 years making me money. Flexlists was hacked / down once because of a stupid fix gone wrong (just winged it before taking off in a plane). I have many of those; downtime etc will cost me literally money and clients. But running it multi-region AWS etc will cut massively in my margins and, as I see in the many companies I do c-level interim/consultancy for, it really actually results in more downtime at most companies because more moving parts. OS updates I carefully study and only do them if they expose an exploitable issue. Which is almost never the case as most exploits actually require server access. The mentioned hack was my own fault and showed me that I must use the demands I have for the systems I write for clients also for myself. I am redoing my applications (some of them) in C#, F#, TLA+ and Coq at the moment. My goal as an engineer is to only need to update the frontend to current standards and let the rest be untouched. I have managed so far.