Even with all the best practices, things outside your control can cause issues. A lot of the code that software engineers write is subject to tiny bits of conti

Even with all the best practices, things outside your control can cause issues. A lot of the code that software engineers write is subject to tiny bits of continual maintenance as small changes in the runtime environment take place. Imagine ten years of those changes deployed all at once. Even something employing all the best practices of ten years ago could be a challenge. You've got a subversion repository somewhere with the code which was compiled to run on Windows XP with Windows Visual Studio C++ 2008 Express but you've abandoned Windows for Linux. If you're lucky the code will compile with the appropriate flags to support C++98 in gcc, but who knows? And maybe there's a bunch of graphical stuff that isn't supported at all anymore or a computational library you used which was only distributed as a closed-source library for 32-bit Windows.