"What failed?" is recorded in the exception, along with the stack trace of how we got there. try...finally can perform best-effort cleanup, it's just like "defe

"What failed?" is recorded in the exception, along with the stack trace of how we got there. try...finally can perform best-effort cleanup, it's just like "defer" with block scope that fits the rest of the language. But it's not that unusual for server hardware to abruptly die, and no error handler can recover from that. "Uploaded file but didn't set metadata" has to be handled in the design phase. Another server needs to notice there may be some unfinished work (often by retrying idempotently).