System Workbench for STM32

Most of the displayed error are due to misinterpretation by Eclipse CDT. You can remove then by rebuilding the index (Right click on the project, Index > Rebuild)

On console view, it says that the Error_Handler() does not exists. By default CubeMX should generate it in main.c, maybe something wrong happens in the generation process.

Here the default function :

/**
  * @brief This function is executed in case of error occurrence.
  * @param None
  * @retval None
*/
void Error_Handler(void) {
	/* USER CODE BEGIN Error_Handler */
	/* User can add his own implementation to report the HAL error return state */
	while(1)
	{
	}
	/* USER CODE END Error_Handler */
}