Seven and a half years later I make sure that I pass that knowledge on to my junior colleagues. I'm proud to say that just in the past 2 weeks I've said this twice to one of my younger team-mates, a recent hire, "don't be afraid to break things!"
"Don't be afraid to break things as long as you have a backup".
It might be a simple version of the previous code, database copy or even the entire application. Do not forget to backup. If everything fails, we can quickly restore the previous working version.
Every production deployment should involve blowing away the prior instance, rebuilding from scratch, and restarting the service; you are effectively doing a near-full "restore" for every deployment, which forces you to have everything fully backed up and accessible...
Any failure to maintain good business continuity practices will manifest early for a product / employee / team, which allows you to prevent larger failures...
In the world where data needs to be maintained, this is not necessarily an option. In the bank where I work, we deploy new code without taking any outage (provide a new set of stored procedures in the database, then deploy a second set of middleware, then a new set of front-end servers, test it, then begin starting new user sessions on the new system; when all old user sessions have completed the old version can be turned off). Taking down the database AT ALL would require user outages. Restoring the database from backup is VERY HARD and would take hours (LOTS of hours).
That being said, we do NOT test our disaster-recovery and restore procedures well enough.
The bug is in the part that I though it was so obvious, I missed some check.
it first builds inefficieny at the technical level then at the business level, finally it causes issues at the cultural level, and thats when the smart people start leaving.
I was handed a legacy codebase with zero tests. I left a few small bugs in production, and got absolutely chewed out for it. It was never an issue with our processes, it was obviously an issue with the guy they hired who had 1 intro CS class and 1 rails hobby project on his resume. The lead dev never really cared that we didn't have tests, or a careful deploy process. He just got angry when things went wrong. And even gave one more dev with even less experience than I had access to the code base.
It was a mess and the only thing I was "learning" was "don't touch any code you don't have to because who knows what you might break" which is obviously a terrible way to learn as a junior dev (forget "move fast and break things" we "move slowly and work in fear!"). So I quit and moved on, it was one of the better decisions I've ever made.