Hi Angus, Thank you for the detailed and very helpful response and the test you made What ESP-IDF version are you using? I was able to use the same settings you have here (including partition table) and enable secure boot on a fresh chip just now, running the current Github master branch (77eae33a7)...

I just enabled secure boot together with encrypted flash for the very first time. While trying to follow documentation I must have missed something, as make monitor displays in a loop: rst:0x10 (RTCWDT_RTC_RESET),boot:0x17 (SPI_FAST_FLASH_BOOT) configsip: 0, SPIWP:0xee clk_drv:0x00,q_drv:0x00,d_drv:...