With the update from SDK 2.4.2 to 2.6.0, the hardware setting and initialization procedures have changed. The project structure has changed accordingly.

The main changes are as follows.

• Changed to copy the resources that were referenced while placed in the SDK folder to the project folder.
• HardwareConfigurator is no longer compatible with Bluetooth products. Accordingly, .hwconf (Hardware Configurator project file), /src/InitDevice.c and /src/InitDevice.h have been removed from the project.
• The initialization code has changed as follows. Along with that, hal-config.h, init_mcu.c, init_board.c, init_app.c, etc. have been added.

--------------------------------------------------
//Change before
void main(void)
{
/* Initialize peripherals */
enter_DefaultMode_from_RESET();

/* Initialize stack */
gecko_init(&config);


//after change
void main(void)
{
// Initialize device
initMcu();

// Initialize board
initBoard();

// Initialize application
initApp();

// Initialize stack
gecko_init(&config);
--------------------------------------------------

More information can be found on the SiliconLabscommunity site here.