The error message indicates that the wxmsw32ud_gcc_custom.dll file is missing. This DLL file is likely a dependency of your application, and it needs to be included alongside your executable for it to run properly. Make sure you have this DLL file available and that it is placed in the same directory as your executable.
Static Linking: If possible, consider statically linking the necessary libraries into your executable during the compilation process. This will eliminate the need for external DLL files and make your executable truly standalone. However, keep in mind that this may increase the size of your executable and could have licensing implications for certain libraries.