Target memory map unknown

PyOCD could not determine the flash region for this MCU. The target was probably auto-detected as generic Cortex-M without a memory map.

FLASH_NO_BOOT_MEMORY

Symptoms

  • Flashing fails saying the flash region / memory map is unknown.
  • The target connects and reads fine — only flashing refuses to run.
  • The target shows as a generic Cortex-M instead of your part number.

Likely causes

  • SWD identifies the core (Cortex-M4, M7, …) but not the exact chip; without an exact part, pyOCD falls back to generic cortex_m, which deliberately has no flash algorithm or memory map.
  • The Target selector was left on auto-detect for a part that cannot be uniquely identified over SWD alone.

How to fix it

  1. Select your exact MCU

    Open the Target selector in the MCUHex footer and pick the full part number (e.g. STM32G474RETx). This loads the flash algorithm and memory layout for the chip.

  2. Flash again

    Retry the flash — with a concrete target selected, the operation should proceed.

  3. Part missing from the list?

    If your exact part number is absent, pick the closest same-family/same-flash-size variant, and report the missing part via feedback so it gets added.

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