rst:0x10 (RTCWDT_RTC_RESET) boot loop
What it looks like
rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT) flash read err, 1000
What it means
The low-level RTC watchdog reset the chip, usually because it could not get through boot. Repeated over and over, it is a boot loop that happens before your sketch runs.
Likely causes
- Something wired to GPIO 12 on the classic ESP32 holding it high at reset, which sets the wrong flash voltage.
- Unstable power during boot.
- Corrupted or wrongly flashed firmware.
How to fix it
- Disconnect everything except USB and reset. If it boots, add parts back one at a time.
- Keep GPIO 12 free on the classic ESP32, or make sure nothing pulls it high at reset.
- Erase the flash and flash again.
Paste your full log
The lines around the error usually say more. Paste everything from the reset to the backtrace and the crash translator explains each part. It runs in your browser; nothing is sent anywhere.
From the hall of flames
- Works on the bench, boot loops in the enclosure: Something wired to GPIO 12 held it high at reset. That pin selects the flash voltage, so the flash chip was run at the wrong one.