Java's famous marketing pitch was "Write Once, Run Anywhere" – the promise that your code would work seamlessly across different platforms. Reality check: it's more like "Write Once, Debug Everywhere." Between JVM quirks, platform-specific bugs, dependency hell, and those delightful NullPointerExceptions that somehow only appear in production, you'll be debugging on Windows, Mac, Linux, and probably your smart fridge too. The dream of universal compatibility meets the nightmare of universal troubleshooting. Nothing says cross-platform like spending your afternoon figuring out why your app works perfectly on your machine but crashes spectacularly on your colleague's setup.