Jim Bird has taken a look at how much is technical debt costing you. Nice to see that he ignores the dollar estimates per line of code that some authors use and just uses a simple $$$ through to $ notation.
$$$ Making a fundamental mistake in architecture or the platform technology – you don’t find out until too late, until you have real customers using the system, that a key piece of technology like the database or messaging fabric doesn’t scale or isn’t reliable, or …
$ Missing or poor error handling and exception handling. It will constantly bite you …