It is especially important to use this function to free memory allocated by the library on Windows. The C standard library is implemented in dynamic link libraries (DLLs) known as the C run-time (CRT). Each version of Visual Studio comes with two CRT DLLs (debug and release) and allocating and freeing across DLL boundaries can cause resource leaks and subtle bugs due to heap corruption.
Only use this function to free memory allocated by the HDF5 Library. It will generally not be safe to use this function to free memory allocated by any other means.
Even when using this function, it is still best to ensure that all components of a C application are built with the same version of Visual Studio and build (debug or release) and thus linked against the same CRT.