esptool fails sporadically, idf.py flash required

[vbpieter]

After flashing ~150 custom ESP32C3 boards, 5 fail to connect using https://github.com/espressif/esptool v5.3.0/v5.3.1
They either: throw 'Possible serial noise or corruption (0x45)', 'Guru Meditation Error (illegal instruction)' or hangs after 'Running stub flasher...'

But flashing with https://github.com/espressif/esp-idf v5.5.5 `idf.py flash` works and after this successful flash, the esptool works as expected.
Any idea why this is the case?

[jarda-burian]

Hello @vbpieter, can you please tell me if you use UART or USB-Serial-JTAG for flashing? Also esptool version you have in the esp-idf v5.5.5, thanks.

[vbpieter]

We're using USB to flash.
The esptool.py bundled with ESP-IDF 5.5.5 is v4.12.0

[jarda-burian]

Can you please try esptool --no-stub option to see if that is the issue? V4 esptool always works and V5 always fails? If only stub fails I have a suspicion that CPU clock increase is the root cause, I can fix that quite soon, but need it to be tested if possible. If you are willing to try, can you please open issue in https://github.com/espressif/esp-flasher-stub? Only if the --no-stub works, thanks.