Do you have pullup resistors on SD card data lines? Sorry, I don't understand what 'internal pullup registers' means @ESP_igrr "Internal" means "inside" or "on board". My sd card board has no pull up resister by itself. @rudi looks the connection like the second? You must itself pullup the lines! p...

I just tried SDIO example (https://github.com/espressif/esp-idf/tree/master/examples/storage/sd_card). 1bit mode works, but 4bit mode does not work. Connections are ok (correctly as https://github.com/espressif/esp-idf/tree/master/examples/storage/sd_card#hardware). My SD card board has no internal ...