Why does the first debug-usart-init work and not the second?

#include "stm32f4xx_hal.h"
static UART_HandleTypeDef UartHandle;
 
void Setup( void ) {
 GPIO_InitTypeDef GPIO_InitStruct;
 
 
 /* STM32F4xx HAL library initialization:
 - Configure the Flash prefetch, instruction and Data caches
 - Configure the Systick to generate an interrupt each 1 msec
 - Set NVIC Group Priority to 4
 - Global MSP (MCU Support Package) initialization
 */
 HAL_Init();
 
 SystemClock_Config(); /* Configure the system clock to 180 MHz */
 
#if 0
 // **** THIS WORKS ****
 // Nucleo DEBUG = PA2/AF7/USART2
 __HAL_RCC_GPIOA_CLK_ENABLE();
 GPIO_InitStruct.Pin = GPIO_PIN_2 | GPIO_PIN_3;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_PULLUP;
 GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct); // PA2 = TxD2, PA3 = RxD2, AF7
 
 UartHandle.Instance = USART2;
 UartHandle.Init.BaudRate = 38400;
 UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
 UartHandle.Init.StopBits = UART_STOPBITS_1;
 UartHandle.Init.Parity = UART_PARITY_NONE;
 UartHandle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 UartHandle.Init.Mode = UART_MODE_TX_RX;
 UartHandle.Init.OverSampling = UART_OVERSAMPLING_16;
 if(HAL_UART_Init(&UartHandle) != HAL_OK) Error_Handler();
#else
 // **** This does NOT work ****
 // Display debug = PC10/AF7/USART3
 __HAL_RCC_GPIOC_CLK_ENABLE();
 GPIO_InitStruct.Pin = GPIO_PIN_10 | GPIO_PIN_11;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_PULLUP;
 GPIO_InitStruct.Speed = GPIO_SPEED_LOW;
 GPIO_InitStruct.Alternate = GPIO_AF7_USART3;
 HAL_GPIO_Init(GPIOC, &GPIO_InitStruct); // PC10 = TxD3, PC11 = RxD3, AF7
 
 UartHandle.Instance = USART3;
 UartHandle.Init.BaudRate = 38400;
 UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
 UartHandle.Init.StopBits = UART_STOPBITS_1;
 UartHandle.Init.Parity = UART_PARITY_NONE;
 UartHandle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 UartHandle.Init.Mode = UART_MODE_TX_RX;
 UartHandle.Init.OverSampling = UART_OVERSAMPLING_16;
 if(HAL_UART_Init(&UartHandle) != HAL_OK) Error_Handler();
#endif
}