I’m testing a USB CDC example on STM32F407IGH generated by STM32CubeMX. The Stm32 device is correctly recognized by the PC system as STMicroelectronics Virtual COM Port but has warring

This device cannot start. (Code 10)
{Device Timeout}
The specified I/O operation on %hs was not completed before the time-out period expired.

The corresponding serial port also cannot be opened by the Serial Debug Assistant.

What I expected:
My goal is to establish data communication between STM32 and PC through built-in USB port, as a more convenient alternative of UART.

In this program, STM32 should establish communication to Serial Debug Assistant. If I add

static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
{
  /* USER CODE BEGIN 6 */
  CDC_Transmit_FS(Buf, *Len); //loopback
  ...

It’s COM port should echo what I’ve send.

Following are Details:

Environment and drivers:
Windows11-22631.3447 STMicroelectronics Virtual COM Port 1.4.0.0 x64 (I’ve tried using Microsoft’s generic driver, but the result is the same)

Program setting:
All the results in this post are reproduced in a clean MDK-ARM project generated by CubeMX.

USB_OTG_FS is configured as device_only mode (default setting: PA11&PA12, 48MHz clocks).
USB_DEVICE IP mode for FS is C.D.C..

The minimum stack/heap size is expanded to 0x4000 / 0x2000.(I’ve tried other scales, didn’t work)

I have supplemented the CDC_SET_LINE_CODING and CDC_GET_LINE_CODING in "usbd_cdc_if.c".

/* USER CODE BEGIN PRIVATE_VARIABLES */
USBD_CDC_LineCodingTypeDef LineCoding =
    {
    115200, /* baud rate*/
    0x00,   /* stop bits-1*/
    0x00,   /* parity - none*/
    0x08    /* nb. of bits 8*/
    };

static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
.
.
.
case CDC_SET_LINE_CODING:
    LineCoding.bitrate    = (uint32_t)(pbuf[0] | (pbuf[1] << 8) |
                            (pbuf[2] << 16) | (pbuf[3] << 24));
    LineCoding.format     = pbuf[4];
    LineCoding.paritytype = pbuf[5];
    LineCoding.datatype   = pbuf[6];

break;

case CDC_GET_LINE_CODING:
    pbuf[0] = (uint8_t)(LineCoding.bitrate);
    pbuf[1] = (uint8_t)(LineCoding.bitrate >> 8);
    pbuf[2] = (uint8_t)(LineCoding.bitrate >> 16);
    pbuf[3] = (uint8_t)(LineCoding.bitrate >> 24);
    pbuf[4] = LineCoding.format;
    pbuf[5] = LineCoding.paritytype;
    pbuf[6] = LineCoding.datatype;
break;

code generation is all fine.

reference:stackoverflow

Hardware connection:
STlink debugger to PA13&PA14 and MricoB port on PA11&PA12 connected to PC USB without adapter.

Report captured by USB Device Tree Viewer:

...
    ----------------- Device Qualifier Descriptor -----------------
Error                    : ERROR_GEN_FAILURE  (because the device has problem code CM_PROB_FAILED_START)

      -------------------- String Descriptors -------------------
String descriptors are not available  (because the device has problem code CM_PROB_FAILED_START)