Unsupported file format

Only .hex, .bin, .elf, and .axf firmware files are supported.

FLASH_UNSUPPORTED_FORMAT

Symptoms

  • The selected file is rejected before flashing starts.
  • You picked a file your toolchain produced, but MCUHex refuses it.

Likely causes

  • The file is not one of the supported formats: .hex (Intel HEX), .bin (raw binary), .elf / .axf (linked image with symbols).
  • A build byproduct was selected by mistake (.map, .o, .a, archive or compressed file).
  • A .bin without base-address context — raw binaries carry no address, so MCUHex needs the correct flash base to place them.

How to fix it

  1. Pick a supported artifact

    Use your final linked output: the .elf/.axf from the linker, or the .hex/.bin your post-build step produces.

  2. Generate .hex from .elf if needed

    Any ARM GCC toolchain can convert the linked ELF into Intel HEX.

    arm-none-eabi-objcopy -O ihex firmware.elf firmware.hex

  3. Prefer .elf when monitoring

    Flashing the same .elf you load for symbols keeps the firmware and symbol addresses guaranteed-consistent — one artifact, no mismatch.

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