Apparently, the use_helper() function is case-sensitive. If the user calls use_helper('form'), the call succeeds on Windows, because the filesystem is not case-sensitive. However, the same call on Linux results in an exception, because the filesystem is case-sensitive. The name of the code file in the symfony codebase is "FormHelper?.php," and the function is looking for "formHelper.php," with a lowercase "f."
This lost me several hours of work with my program, which is developed on Windows Vista and hosted on Linux. In this case, the problem was not discovered for a month after release and had caused over a thousand 404 errors that I was unaware of. To prevent the OS dependency, perhaps the function should check for both the lowercase and the uppercase versions of the name. Alternatively, an exception could be thrown in both cases so that the error is caught in development, and not in production. Either way, making the behavior consistent across operating systems would surely save a lot of wasted time.
