Indeed, I had 'bad alloc' because my application is compiled in debug, and Qt libraries I have are release libraries. Currently I don't have the debug version of Qt libraries.

Now, for the initial issue to register rcc file : generally, when you develop with Qt, it's better to always use 'Q' objects, especially for strings. It's a bad idea to try to mix 'standard' strings with QStrings.

So, since I manage all paths and strings with QDir and QString, all works fine.