flash read err, 1000
What it looks like
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT) flash read err, 1000
What it means
The bootloader could not read the flash chip at offset 0x1000, where the second-stage bootloader lives on the classic ESP32. Either the flash is not powered correctly or it was set up with the wrong mode.
Likely causes
- GPIO 12 pulled high at reset on the classic ESP32, which selects 1.8 V flash on a 3.3 V flash chip.
- Wrong flash mode or frequency in the upload settings.
- A damaged flash chip, which is rare.
How to fix it
- Disconnect whatever is on GPIO 12 and reset.
- Set Tools > Flash Mode to DIO and Flash Frequency to 40 MHz, then upload again.
- If GPIO 12 must be used, burn the flash voltage eFuse with espefuse.py set_flash_voltage 3.3V. That is permanent, so be sure of your flash chip's voltage first.
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.