Nodemcu 1.0 and boot mode (1,6) after soft reset

Question

I have a problem with a nodemcu 1.0 (lolin) board. Sometime a soft reset is performed from the watchdog and the board freezes in boot mode (1,6) (I have to manually reset the board to restart it). I have read many thinks on this topic and I have carefully avoided to use the GPIO0, GPIO2 and GPIO15. I have also verified that these pins are correctly pulled-up (GPIO0 and GPIO2) and pulled-down (GPIO15) but when the board frezes I have noticed that the voltage of the GPIO0 is not 3.3V but 2.0V. Has anybody experienced a similar problem? Could you help me in solving it?

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Answer 1

The esp8266 has a bug (documented). After Serial upload the program is started without reset and then at soft reset the state of "start bootloader" is still active.